References on Crossref

Solving your technical support questions in a snap!

Isaac Farley — Thu, 25 Jan 2024 00:00:00 +0000

My name is Isaac Farley, Crossref Technical Support Manager. We’ve got a collective post here from our technical support team - staff members and contractors - since we all have what I think will be a helpful perspective to the question: ‘What’s that one thing that you wish you could snap your fingers and make clearer and easier for our members?’ Within, you’ll find us referencing our Community Forum, the open support platform where you can get answers from all of us and other Crossref members and users. We invite you to join us there; how about asking your next question of us there? Or, simply let us know how we did with this post. We’d love to hear from you!

A little about us and what drives the team

I’m fortunate to manage a great team - Evans, Kathleen, Paul, Poppy, and Shayn - who enjoy and are hardwired to guide. We have different strengths and interests, but the thing that unites us is that we are energized when we can unpick tricky problems for all of you, our members and users. In 2023, the technical support team answered around 11,000 questions from all of you. We do that with one-to-one requests sent to us via email and within our support center (using a closed-source software called Zendesk). And, we’ve been providing more and more support in our Community Forum, where we’re aiming for open interactions, so we can all learn from the rich exchanges with all of you (the Forum has an integration with Zendesk, so posts made in the Forum are delivered to us there, so our team won’t miss any of your questions).

We established in the previous paragraph that we have a great technical support team who all pride themselves on helping you. But we’re also human; the reality is that many of those ~11,000 technical support questions asked of us in 2023 were repetitive, and there are always trends in the questions asked. That’s another important reason why we’re hoping to have more and more of these questions asked and answered within our Community Forum; again, so we can all learn from one another. We know certain parts of content registration, metadata retrieval, and everything in between are, well, complicated. The Crossref learning curve can be steep for all of us. Collectively, our technical support team has more than 25 years of Crossref experience, and we’re continuously learning new things about the Research Nexus and the scholarly ecosystem from one another and all of you.

Learning through this complexity is one of the most enriching parts of our days. Our daily stand-up, modeled off of different software development methodologies, where together we troubleshoot tangly questions from all of you, share ideas, and just keep up-to-date on the latest from across the organisation leads to a lot of knowledge exchange. So, years ago, we decided to transform the issues we discuss in those stand-ups into public-facing posts in our Community Forum. It gave us the opportunity to share much-needed examples in a new community space; and, we knew, since these were the issues we were all discussing and learning from ourselves, that many of you would also benefit from us surfacing the topics openly. We call these posts tickets of the month, since the majority of topics we discuss have originated from tickets in our support center.

Examples of some of the most popular topics in the last two-plus years have been:

Snapping our fingers

Like I said, these posts originated from real-life questions of us from our community members. In most cases, we’ve been asked these questions by many of you. These Community Forum posts are our attempts to unlock understanding of our services, rich metadata, or the larger Research Nexus. Said another way: we all see value in putting in the effort to post one more example or answer that nuanced question. Perhaps one of our posts will include an example that really resonates with you and/or your work.

In that spirit, I asked Evans, Kathleen, Paul, Poppy, and Shayn to answer this question below (yes, I’m going to weigh in, too):

What’s that one thing that you wish you could snap your fingers and make clearer and easier for our members?

Evans, Technical Support Specialist

As a publisher and a Crossref member, at one point or another, you might have made a mistake in the metadata deposited for a given DOI. I’m sure after the slight ‘shock’, the next question you had in mind was, ‘How can I correct this mistake?’ Well, here is a simplified guide on how to do that correction/update!

Can I modify/ update the metadata of a registered DOI? As indicated by my colleague Shayn below in this blog post, Crossref DOIs are designed to be persistent (and cannot be changed/deleted once registered). And YES, you can update the metadata associated with any of your registered DOIs whenever necessary, at no additional fee.

How can I perform a standard metadata update? To add, change, or remove any metadata element from your existing records, you generally just need to resubmit your complete metadata record with the correct/new changes included. How you choose to update a DOI metadata record is highly dependent on the content registration tool/platform you are using/comfortable working with, as described below:

OJS: Navigate to the article record you wish to update, add in your new metadata/delete relevant metadata fields, and deposit it again using the Crossref import/export plugin. You must be running at least OJS 3.1.2 and have the Crossref import/export plugin enabled.
Web deposit form: Open the web deposit form, and re-enter all the metadata, including the new changes - leave the relevant field blank to delete it, or add in your new metadata to update it - and resubmit the form (note: there are a handful of exceptions to this for the web deposit form).
Depositing XML files with Crossref: Make changes to the relevant XML file and resubmit it to Crossref via the admin tool. When making an update, you must supply all the bibliographic metadata for the record being updated, not just the fields that need to be changed. During the update process, we overwrite the existing metadata with the new information you submit, and insert null values for any fields not supplied in the update. This means, for example, that if you’ve supplied an online publication date in your initial deposit, you’ll need to include that date in subsequent deposits if you wish to retain it. Note that the value included in the element must be incremented each time a DOI is updated.

If you’re looking for real-life examples of other members who have updated their metadata, the Community Forum is a great starting point. If you have follow-up questions on any of the existing threads, I invite you to post a message today.

Kathleen, Technical Support Specialist

One of my favorite types of queries to tackle are those regarding content registration problems. I love a good mystery and getting to the bottom of why that pesky submission just didn’t succeed. Sometimes members come to us with an error message and specific questions about what has gone awry. But, in fact, two of the most common questions we receive are: 1) I deposited something; did it work? and 2) I deposited something; why isn’t it showing up?!

To address the first question of whether your submission went through or not, I wrote a forum post back last June talking about how to use the admin tool to see whether your registration was successful or not. We know there are also email alerts and perhaps status messages within your own registration platform, but using the admin tool is a great way to concretely check where your submission has ended up. If it’s not there, we didn’t get it!

Using the admin tool is also a great way to get more details about the submission and more information in case the submission happened to fail. You may have had the experience in which you contacted us with a question about a failed deposit, and we asked you for the submission ID. You can find that info in the admin tool! And we ask for that, because that helps us get to the bottom of those error message mysteries.

And, as for the second question of when will your DOI be active, my colleague, Paul, wrote a fantastic post on the forum (with an excellent flowchart and all!), explaining when you can expect to see your DOI up and running. Often members will submit a deposit and expect the DOI to resolve immediately. When that doesn’t happen, many think that something has gone wrong or perhaps there is an error, but, in fact, our systems may still be updating and processing the metadata.

I recommend giving these two posts a read if you’re at all concerned about whether you’re depositing your content correctly or not. Hopefully, they’ll help ease your content-registration worries.

Isaac, Technical Support Manager

Oh, thanks for asking! Many of our members, after receiving one of our reports, will respond to us in support with a message similar to: ‘What did I do wrong? Please help me fix this. I don’t want to be out of compliance!’

The receipt of one of our reports does not necessarily mean that you’ve done anything wrong. In truth, the reports we send to our official member contacts are produced using very simple logic. It’s true that they may signal larger, more complicated problems, but we really need your help to determine next steps (and, in some cases, no action is needed because there is no issue for members to fix (e.g., many failed resolutions within the resolution reports)).

Let’s look at the conflict and resolution reports since those are the reports we get the most questions about:

Conflict reports are the most complicated of our reports to navigate. But, the reports are generated using simple logic: if you register two or more DOIs with matching bibliographic metadata, we’ll flag those DOIs as being in conflict, which will generate a warning message at the time of registration and a subsequent conflict report. When members receive this report, we often get the sense that members simply want us, the technical support team, to tell them how to fix it. The problem is we don’t know your content, so we don’t know if the two DOIs do represent a duplicate, or if both DOIs, while having very similar bibliographic metadata, are legitimate and will be maintained going forward (e.g., for errata). Paul wrote a great post in our community forum about what conflicts are and how to resolve them.

Resolution reports, like conflict reports, are generated using simple logic: a resolution is the result of a click on that DOI. If a DOI has been registered, that click results in a successful resolution. If that DOI has not been registered, that click results in a failed resolution. Our monthly report is a count of those resolutions - successful and failed. Failures can represent content registration errors in a member’s workflow. Or, they can signal that an end user has made a mistake when attempting to click the DOI in question. So, for example, an end user perhaps added an extra period onto their DOI link. Instead of trying to resolve https://doi-org.pluma.sjfc.edu/10.5555/cupnfcm2wj, a legitimate DOI, they added a period to the end and tried to resolve https://doi-org.pluma.sjfc.edu/10.5555/cupnfcm2wj. instead. That extra period at the end of the DOI has made it a completely different DOI that is not registered with us, thus they get a failed resolution. This is pretty common. For members with content being regularly clicked, there will be user errors in the logs appearing as failed resolutions. The first question members should ask themselves when reviewing the failed .csv report within the resolution report is: ‘are any of these DOIs legitimate DOIs that I thought we had registered?’ We have more on the basics of resolution reports also over in our Community Forum.

Paul, Technical Support Specialist & R&D Support Analyst

I know we were asked to name “one thing” but I have two that are closely related. May I snap my fingers twice and fix two issues? [Of course, Paul! Take it away!]

Paul’s first snap

One of the most asked questions we get in support is “why is my DOI not working?” 90% of the time it is down to a failed submission. A good proportion of those failures are a result of title mismatches between the deposited container title and the one we have stored on the system here. There are other error messages that occur, too, which I wrote about back in 2020.

So, “why do we fail submissions because of title differences?” You might ask.

Well, the title and ISSN/ISBN and/or the title level DOIs act like locks to the title record, which need the right keys to unlock the title so that you can add or update the records against it. So if you don’t match what was in the original submission, you get a failure. Without that stringent check, we would have way too many iterations of titles and matching to those would be a nightmare. Not to mention sorting those DOIs into one container in the REST API.

Isaac wrote a great forum post about these title-level issues as well.

If a title update is required due to an error with an original title deposit, then these need to be made by the support team, so get in touch with us on the Community Forum.

And, a second

Permissions against titles and DOIs: Lots of our members don’t realise that each DOI has its own permissions against the prefix that currently ‘owns’ or is associated with that DOI in the background.

It would be fair to assume you can tell just by looking at a DOI who the current publisher is, based on the prefix at the start —but that’s not always the case. Things can (and often do) change. Individual journals get purchased by other publishers, and whole organisations get bought and sold.

What you can tell from looking at a DOI prefix is who originally registered it, but not necessarily who it currently belongs to. That’s because if a journal (or whole organisation) is acquired, DOIs don’t get deleted and re-registered to the new owner. The update will of course be reflected in the relevant metadata, but the prefix on the DOI will stay the same. It never changes—and that’s the whole point, that’s what makes the DOI persistent. Isaac also wrote this in much more detail and explains the internal Crossref processes in his blog “What can often change, but always stays the same?“

These permissions are very important to understand when it comes to title transfers and working with updating your metadata against transferred DOIs to prevent duplicate DOIs for the same work.

Poppy, Technical Support Contractor

As a researcher myself, I’d like to talk about references in a journal article, book, conference paper, etc. (I’ll just use ‘article’ going forward for simplicity). These are the references included in an article by the author. References in one article result in citations for another article. It’s the thing every author dreams of and accruing citations can be a big deal for authors, journals, and publishers.

For readers, articles with no references can be less discoverable using systems that use citation links for relevance, and that discoverability is of critical importance for our members who decide to register references with us. We all want your content to be shared, cited, linked, and used far and wide.

We receive many questions from authors asking why citations don’t show up; it’s usually due to metadata deposits with no references included. There may be an assumption that our process is like Google Scholar, which crawls full text and websites. This misunderstanding has a big impact on references and citation counts. However, as we do not store a copy of the paper, our intake system does not extract references from the article, regardless if they have a DOI. This is one of the main reasons that Crossref citation counts are lower than services that use extraction methods. We only store the data that a publisher registers and maintains with us. On deposit of a metadata record that includes references, our system performs a matching process - if there is a match, a cited-by connection is applied to the metadata. With deposits with no references, however, there is no data to match to other articles (and, therefore limitations on the discoverability and no cited-by count increase).

An article with no references has big impacts for the authors, the journal, the publisher, researchers, and ultimately, the readers. This can mean decreased distribution of the content itself, reduced citation counts for cited articles, lower impact metrics for journals, and can ultimately affect value for publishers. For example, researchers just don’t include articles without references for scientometric analysis.

Our documentation on references includes the elements for both structured and unstructured data. Including the DOI in the structured data is best practice as it provides a precise location with rich data for matching. If the matcher does not see a link between the deposited DOI and the cited DOI at the time of deposit, then the references are stored to be crawled with other matching algorithms later. So, we’re always working to create those rich cited-by linkages between works (raising the content’s profile and overall discoverability), no matter when you register reference metadata. You can also see how your publisher is doing on depositing references by viewing their Participation Report. If you are an author, you can check if your DOIs that were registered contained any references by using our REST API. Don’t see them? You can always contact the editor of the journal or the publisher that published your paper and ask them to add them. Didn’t hear back? Just drop us a line in the Community Forum, we’re happy to help.

Shayn, Technical Support Specialist

Let’s ‘zoom out’ to the big picture. What are DOIs for? What makes them useful? What are we all doing here anyway?!

There are a lot of different answers to those questions. It’s a complex picture. But, way back in the late ‘90s, the DOI system was designed in order to allow for the creation of unique and persistent identifiers. Crossref members use these identifiers to represent their research outputs and publications. This allows for reliable linking to those items, and the ability to identify and communicate the relationships between them, notably (but not exclusively!) citation relationships.

So, what do we mean when we say that Crossref DOIs should be unique and persistent? In basic terms, unique means that there is only a single Crossref DOI registered for a given citable research output. And, persistent meaning that the DOI associated with a given research output today will continue to be associated with, and link to, that same research output indefinitely into the future.

Yes, there are some grey areas, and we know that everything doesn’t always work 100% perfectly all the time. But, the more deviations from persistence and uniqueness, the harder it becomes for end-users, publishers, Crossref, and other services which make use of our metadata to reliably find research outputs and reliably relate them to one another. It weakens the value and utility of DOIs for everyone.

So, what does this mean in practice?

Be certain that every item you register with Crossref is something you can maintain in the long-term.
- Have an arrangement with an archive that can take responsibility for your content if your organisation stops hosting it or ceases to exist.
- Don’t register things that you know will only exist for a short time.
When you’re about to register new content, be absolutely sure that it hasn’t been registered already, either by your organisation or any other organisation.
- If you acquire a new journal from another publisher, have a process in place to check what content has already been registered and adopt the use of the DOIs registered by the prior publisher for that content. We can always provide a list of the existing DOIs for a journal.
- If you publish books, and have a co-publishing agreement with another publisher, distributor, or hosting platform, be aware that one of those other parties may have already registered DOIs for your books. Adopt the use of those DOIs rather than assigning and registering new ones. And, if you don’t want them to do that going forward, communicate that to your co-publishing partners.
When mistakes happen, inadvertently resulting in duplicate DOIs for a single item, identify them quickly. Alias the new duplicate DOI to the long-standing original DOI, and remove all instances of the new DOI from your website or platform.
Ensure that your publishing software, platform, or journal management system can accommodate DOIs with various prefixes for the same publication. You should be able to use (display, link, update metadata and URLs for) the DOIs registered for older content by any prior publishers as easily as you use the DOIs that you registered yourself for more recent content.

Things like persistence and uniqueness can sound like theoretical abstractions, but they actually play an important role in the day-to-day grind of your publishing operations. Their impact on linking, citing, discovery, and analysis of your content is concrete and important. Thus, it’s not surprising that we often hear from members and others in the research community who share this commitment to persistence, uniqueness, and overall rich, accurate metadata. You’ll see that play out in the Community Forum where members and users get involved to troubleshoot issues, compare notes, and share ideas with us and one another. We appreciate the commitment to the Research Nexus and the overall spirit to serve in this growing community. Like we said at the top, we’re all wired to contribute in this way, so building an open, welcoming space that moves us forward excites us.

Again, we invite you to join the discussion on this and many other Crossref-related topics over in our Community Forum.

Amendments to membership terms to open reference distribution and include UK jurisdiction

Ginny Hendricks — Mon, 04 Apr 2022 00:00:00 +0000

Tl;dr

Forthcoming amendments to Crossref’s membership terms will include:

Removal of ‘reference distribution preference’ policy: all references in Crossref will be treated as open metadata from 3rd June 2022.
An addition to sanctions jurisdictions: the United Kingdom will be added to sanctions jurisdictions that Crossref needs to comply with.

Sponsors and members have been emailed today with the 60-day notice needed for changes in terms.

Reference distribution preferences

In 2017, when we consolidated our metadata services under Metadata Plus, we made it possible for members to set a preference for the distribution of references to Open, Limited, or Closed. Prior to the 2017 change, we acted as a broker of 1:1 feeds of parts of metadata for parts of our community - clearly a role that was not scalable.

We are well underway to pay back technical debt on our 20-year-old metadata system and effectively rearchitect it. We therefore recently needed to decide whether to rewrite code for a capability that hardly any member was using. Just one member has chosen Closed, and Limited was the default for a while, but the vast majority of our members now prefer Open distribution. Additionally, bringing references in line with other metadata significantly simplifies this work and will speed up the technical development.

The Crossref Board discussed the issue in our meeting on 10th March 2022, and voted to remove the reference distribution policy set in 2017. All board motions go on our website, and the wording of this particular motion is:

Resolve that, based on a technical assessment, we will change the reference distribution policy so that all references registered with Crossref are treated the same as other metadata, following a planned transition.

This motion means that 60 days from today—3rd June 2022—all references in Crossref will be open and after that available through our API. As with all other metadata, if members cannot make references available, or do not want them openly distributed, they can choose not to deposit them. However, depositing references is necessary in order to retrieve citation links from our members-only Cited-by API.

Check the documentation for information on how to deposit references and use Cited-by. Also look up your participation dashboard to see if you are already registering references and your current distribution setting.

Sanctions jurisdictions

Following the UK departing from the European Union, we needed to add the United Kingdom as a separate jurisdiction that we must comply with, alongside the United Nations, the United States of America, and the European Union.

Where there are either relevant financial or governance-based sanctions against individuals, organisations, geographic regions, or whole countries, Crossref is legally bound to comply with these four different jurisdictions. These laws supersede our own governing bylaws.

We have launched a new operations and sustainability section of our website, which includes a sanctions page which we will keep updated with any changes and actions we’re taking.

The specific terms that will change

The complete membership terms are online here. In the text below, any text to be removed is shown in ‘strike-through’ text and any additions are in bold. These new terms will be in effect from 3rd June 2022.

5. Distribution of Metadata by Crossref. Without limiting the provisions of Section 4 above, the Member acknowledges and agrees that~~, subject to the Member’s reference distribution preference,~~all Metadata and Identifiers registered with Crossref are made available for reuse without restriction through (but not limited to) public APIs and search interfaces, which enhances discoverability of Content. Metadata and Identifiers may also be licensed to third party subscribers along with an agreement for Crossref to provide third parties with certain higher levels of support and service. For the avoidance of doubt, the scope of Crossref’s distribution (if any) of a Member’s references is based on such Member’s reference distribution preference, as established by the Member in accordance with the “Reference Distribution” page on the Website.

20. Compliance. Each of the Member and Crossref shall perform under this Agreement in compliance with all laws, rules, and regulations of any jurisdiction which is or may be applicable to its business and activities, including anti-corruption, copyright, privacy, and data protection laws, rules, and regulations.

The Member warrants that neither it nor any of its affiliates, officers, directors, employees, or members is (i) a person whose name appears on the list of Specially Designated Nationals and Blocked Persons published by the Office of Foreign Assets Control, U.S. Department of Treasury (“OFAC”), (ii) a department, agency or instrumentality of, or is otherwise controlled by or acting on behalf of, directly or indirectly, any such person; (iii) a department, agency, or instrumentality of the government of a country subject to comprehensive U.S. economic sanctions administered by OFAC; or (iv) is subject to sanctions by the United Nations, the United Kingdom, or the European Union.

As always, please get in touch with us via member@crossref.org with any questions.

Event Data now with added references

Martyn Rittman — Wed, 10 Nov 2021 00:00:00 +0000

Event Data is our service to capture online mentions of Crossref records. We monitor data archives, Wikipedia, social media, blogs, news, and other sources. Our main focus has been on gathering data from external sources, however we know that there is a great deal of Crossref metadata that can be made available as events. Earlier this year we started adding relationship metadata, and over the last few months we have been working on bringing in citations between records.

Our members deposit references alongside other metadata, and we have a lot of them. In fact, we have over 1.2 billion, with hundreds of thousands of new references added each day. While our metadata APIs make it easy to see which works are cited, it is much more difficult to find a list of citations to a specific work. We can make this easier by presenting citations as events in Event Data. Now that the huge majority of our members have responded positively to the Initiative for Open Citations (I4OC) campaign and Crossref’s open-by-default reference policy, the move to make this data available via Event Data is a natural step.

A bumpy ride, but we got there

Adding such a large amount of data means a significant increase in the data coming into Event Data, which has presented some challenges. We’ve known for some time that Event Data is not very stable, but we expected it to cope with the new data coming in. We have mitigated by initially only looking at new data, not trying to immediately back-fill with old references. Unfortunately, even with this limitation it hasn’t been a smooth ride, and our first effort to put references into Event Data uncovered bugs we didn’t know about and we had to walk back the changes. We tried again and found that we were hitting rate limits for our own APIs. This is a sure sign of technical debt: we shouldn’t need to be shifting large amounts of our own data from one place to another, and not at rates that could be putting stress on APIs used by others in the community.

We have managed to work around these problems and I’m pleased to say that we are now adding metadata from reference lists to Event Data. They can be accessed via the Event Data API: https://api-eventdata-crossref-org.pluma.sjfc.edu/v1/events?rows=10&source=crossref&relation-type=references&from-collected-date=2021-10-01

Where to next?

There remains work to be done. We would like to backfill references, and there is also further work to include relationships to objects that have identifiers other than Crossref records (genes, proteins, ArXiv identifiers, and so on). Our work on investigating sources is proceeding and we will be looking to add more next year. While possible, these steps will be costly and time-consuming if we proceed without significant changes to the infrastructure supporting Event Data.

When we started Event Data the volumes of data were much smaller and our infrastructure coped well, but as we’ve said here before, it’s in need of an overhaul. In fact, our recent experience and some other considerations are making us look at some very fundamental changes in how we record events.

We are therefore working on a new data model that will allow events to be stored alongside the rest of our metadata. This work is still in the early stages, but if we are successful it will mean that we won’t need to move data between databases. It will also make it easier to provide access to all of our reference metadata along with other relationships that we’re not currently able to provide, and give us the capacity to add new data sources.

Open references

[EDIT 6th June 2022 - all references are now open by default with the March 2022 board vote to remove any restrictions on reference distribution].

It is worth noting that only open references will be available via Event Data. This covers 88% of works with references at present. Members have the option to deposit references with limited visibility, meaning only Metadata Plus users can access them; or closed visibility, meaning that only the member who owns the cited work can retrieve the citation, via Cited-by.

We encourage our members to make their references open and deposit them as metadata. It makes them usable downstream by thousands of tools that researchers use. Including open references also improves the quality of metadata, and there are reciprocal benefits for the large number of members who openly share their reference data: they contribute to a large, openly available pool of data with many applications that advance research, and drives usage of the content published by our members.

If you are a Crossref member and unsure whether your reference metadata is open or not, check your participation report. This will tell you the percentage of your records with deposited references, and the percentage of those that are open. You can change the reference visibility preference for each DOI prefix that you own by contacting our support team. For guidance on how to deposit references, see our user documentation.

A simpler text query form

Isaac Farley — Tue, 30 Apr 2019 00:00:00 +0000

The Simple Text Query form (STQ) allows users to retrieve existing DOIs for journal articles, books, and chapters by cutting and pasting a reference or reference list into a simple query box. For years the service has been heavily used by students, editors, researchers, and publishers eager to match and link references.

We had changes to the service planned for the first half of this year - an upgraded reference matching algorithm, a more modern interface, etc. In the spirit of openness and transparency, part of our project plan was to communicate these pending changes to STQ users well in advance of our 30 April completion date. What would users think? Could they help us improve upon our plans?

About a month ago, I reached out to the 21,000 plus users we had on record of using STQ since January 2018. We received nearly 85 responses from the messages we sent. Questions ranged from: if we were making changes, would PubMed ID matching be supported? To: What about the reliability of the returned reference links? And: Could we better accommodate larger reference lists?

Many of the users we heard from told us how STQ was critical to their work. I read all these messages. The concerns raised by users were legitimate and much appreciated. We reassessed our project timeline and plans, and decided to shift course. So, what are we doing?

What’s changing?

The previous hurdle of having to register your email address simply to return reference links was confusing and unnecessary. We removed it.
We previously limited the number of monthly reference links to 5,000 per email address. Most didn’t reach the limit, but those who did were frustrated by it and/or found ways around it. We want you to match and register as many references as possible, so we removed the monthly limit too.
Many of you with long reference lists found that you were occasionally reaching our limit of 30,000 characters per submission. Once again, we want you to match and register as many references as possible so we removed the character limit altogether and instead are just looking at the number of references per submission. We now provide space for 1,000 references per submission (We checked. The most references we have ever received via the STQ form in one submission was around 750. Thus, we rounded up.).
We did make a change to the backend of the service. We updated the algorithm we use to return reference links. We think it’s an improvement. Let us know how you find it.

What’s remaining the same?

Core functionality. It’s all in the name. Retrieve DOIs for journal articles, books, and chapters by cutting and pasting a reference or reference list into a simple query box.
PubMed ID matching. You use it. You need it. We’re keeping it.
Deposits. You’ll still need an email address for this, but we won’t ask for it until you’re at the deposit screen.
The interface. We’re still eager to give the user interface a much-needed refresh, but, as many users pointed out to us, there’s still some core functionality that’s important that we need to retain with any interface update. For instance, you need to be able to easily copy and paste reference links into your reference list. That functionality isn’t going anywhere.
Resetting reference links. Submit references, match, reset, and repeat. Many users like the reset button. It’s not going anywhere either.

XML queries

The change to the backend of the service that I mentioned above is not confined to reference matching and depositing for STQ users. XML queries for reference matching are also now powered by that new backend. We think it’s a seamless transition, but if you find it is not, please let us know.

I’m excited for these changes and hope you are too. I invite you to try the simpler and improved STQ form, and let us know what you think.

Linking references is different from registering references

Anna Tolwinska — Wed, 30 May 2018 00:00:00 +0000

From time to time we get questions from members asking what the difference is between reference linking and registering references as part the Content Registration process.

Here’s the distinction:

Linking out to other articles from your reference lists is a key part of being a Crossref members - it’s an obligation in the membership agreement and it levels the playing field when all members link their references to one another.

Registering references when you register your content is completely different. It’s enriching the metadata record that describes your content, and it allows Crossref and others—including non-members—to use them.

Reference Linking

A research article usually includes a reference list of citations to other works that helped inform it. The original function of Crossref was to provide a central service for publishers that enabled them to link to each others’ content from these reference lists—using a DOI as a persistent link. This meant that members of all sizes and in all disciplines could easily link to one another without having to sign hundreds of bilateral agreements.

We made Reference Linking obligatory for Crossref members because it’s fundamental to making content discoverable, and because when everyone links their references, research travels further and benefits everyone.

Registering references

Every single day hundreds of members register and update their metadata with us—and every single day hundreds of organisations search for, extract and use it. To make sure your content is discovered in this process, it’s important to make the metadata you register with us as rich as possible. Rich metadata includes information such as journal title, article author, publication date, page numbers, ISSN, abstracts, ORCID iDs, funding information, clinical trials numbers, license information, and of course—references.

Additionally, registering references is ~~a prerequisite~~ recommended for participating in our Cited-by service—which provides citation counts and lists, and ultimately makes your content more discoverable. [EDIT 7th February 2024 - it is no longer required but highly recommended.]

We know it’s not easy for smaller publishers to deposit references. Read more on how to here. Our upcoming Metadata Manager tool will allow you to register your references at the same time as the rest of your content. This service is currently in development but let us know if you want to try it out. [EDIT 7th February 2024 - Metadata Manager has been deprecated. More info about it here.]

Reference Linking

Reference Linking means adding Crossref DOI links to the reference list for journal articles on your article pages as per this example: https://doi-org.pluma.sjfc.edu/10.1088/1367-2630/1/1/006.

How it works

First retrieve DOIs for all available references either through our human or machine interfaces. Then make sure you use the DOI link in your references and on your article landing page using the Crossref DOI display guidelines.

Why it’s useful

Reference Linking:

Enables you to link to more than 10,000 publishers without having to sign multiple agreements
Helps with discoverability, because DOIs don’t break if implemented correctly
Displays your DOIs as URLs so that anyone can copy and share them
Makes your content more useful to readers
Drives traffic to your website from other publishers.

Is it obligatory?

Yes, within a short time after becoming a member you should be including references.

Registering References

Registering references means submitting them as part of your Crossref metadata deposit as per this example: https://www-crossref-org.pluma.sjfc.edu/xml-samples/article_with_references.xml.

How it works

Whenever you register content with us, make sure you include your references in the submission. You can also add references to your existing content via a metadata redeposit, or our resource-only deposit, or our Simple Text Query form.

Why it’s useful

References registered as part of your metadata:

Make your content more discoverable
Make your content richer and more useful
Are required to participate in our Cited-by service (this service shows what articles cite your article)
Enables discovery of research
Enables evaluation of research
Highlights your contents’ provenance
Helps with citation counts.

Is it obligatory?

No, it’s optional, but strongly encouraged. It is ~~required~~ recommended if you are participating in our Cited-by service. [EDIT 7th February 2024 - it is no longer required but highly recommended].

If you have any questions about reference linking or registering your references please get in touch.

Distributing references via Crossref

Geoffrey Bilder — Fri, 17 Jun 2016 00:00:00 +0000

Known unknowns

If you follow this blog, you are going to notice a theme over the coming months- Crossref supports the deposit and distribution of a lot more kinds of metadata than people usually realise.

We are in the process of completely revamping our web site, help documentation, and marketing to better promote our metadata distribution capabilities, but in the mean time we think it would be useful highlight one of our most under-promoted functions- the ability to distribute references via Crossref.

One of the questions we most often get from members is- “can we distribute references via Crossref?” The answer is an emphatic yes. But to do so, you have to take an extra and hitherto obscure step to enable reference distribution. [EDIT 6th June 2022 - all references are now open by default with the March 2022 board vote to remove any restrictions on reference distribution].

How?

Many members deposit references to Crossref as part of their participation in Crossref’s Cited-by service. However - for historical reasons too tedious to go into - participation in Cited-by does not automatically make references available via Crossref’s standard APIs. In order for publishers to distribute references along with standard bibliographic metadata, publishers need to either:

Contact Crossref support and ask them to turn on reference distribution for all of the prefixes they manage.
Set the reference_distribution_opt element to any for each content item registered where they want to make references openly available.

Either of these steps will allow references for the affected member DOIs to be distributed without restriction through all of Crossrefs APIs and bulk metadata dumps.

Note that by doing this, you are not enabling the open querying of your Cited-by data- you are simply allowing the references that you already deposit to be redistributed to interested parties via our public APIs.

Who?

So who does this now? Well, at the moment not many members have enabled this feature. How could they? They probably didn’t know it existed. At the time of writing this 29 publishers have enabled reference distribution for at least some of their DOIs.

But that’s why we are writing this post. Given the interest expressed by our members, we expect the list to start growing quickly over the next few months. Particularly now that they know they can do it and have clear instructions on how to do it. 🙂

If you are of a geeky persuasion and want to see the list of publishers who are doing this, you can check via our API.

The following query will just show you the total number of members who are distributing references for at least some of their DOIs.

https://api-crossref-org.pluma.sjfc.edu/v1/members?filter=has-public-references:true&rows=0

And this query will allow you to page through the member records and see who is distributing references.

https://api-crossref-org.pluma.sjfc.edu/v1/members?filter=has-public-references:true

That cool, but can you see how many total DOIs have reference distribution enabled? No, but will will be adding that capability to our API soon.

OMG! OMG! OMG! Does this mean I can get references from api.crossref.org?

Yep. But before you get too excited- note above that not many of our members are doing this yet and that our API is still being updated to allow you to better query this information. At the moment references are not included in our JSON representation- they are only included in our XML representation. You can get the XML for a Crossref DOI either through content negotiation, or by using the following incantation on our API (using an eLife DOI as an example):

~~https://api-crossref-org.pluma.sjfc.edu/v1/works/10.7554/eLife.10288.xml~~

~~As we update our API to better support querying DOIs that include references, you will see the new functionality reflected in our documentation at:~~

Yes. 🤗. See the API docs below.

https://api-crossref-org.pluma.sjfc.edu