The Crossref Curriculum


Registering references means submitting them as part of your Crossref metadata deposit. It is optional, but strongly encouraged. Registering references is a prerequisite for participating in our Cited-by service, which shows the works which cite your work. Note that registering references is not the same as reference linking - learn more about the differences.

The benefits of registering references as part of your metadata include:

  • making your content more discoverable (especially if your references are open),
  • enabling evaluation of research, and
  • helping with citation counts.

Learn more about the Initiative for Open Citations (I4OC).

Whenever you register content with us, make sure you include your references in the submission.

Including references (or adding them to an existing deposit) can be done by:

  • Crossref XML plugin for OJS: you can include references in your initial deposit, or add them later using the OJS reference linking plugin.
  • Web deposit form: the web deposit form can’t currently be used to add references when you first register your content, but you can use Simple Text Query to match references and add them to an existing record.
  • Metadata Manager: there’s a field where you can add references and Metadata Manager will even match your references to their DOIs. If you want to add references to an existing deposit, simply find the existing journal record, add your references, and resubmit. Learn more about updating article metadata using Metadata Manager.
  • Direct deposit of XML: you can include references in your original deposit, or add them later by your usual deposit method. Learn more in our references markup guide.

Including references in your XML

When depositing references as part of your content registration XML, mark up individual citations according to our deposit schema section. For example:

<citation key="ref1">
  <journal_title>Current Opinion in Oncology</journal_title>

Marking up each element creates a structured citation. This allows us to be very precise when identifying potential matches with registered DOIs.

If you know the DOIs of individual citations, include them:

<citation key="ref2">

All citation elements are optional, but please submit as much information as possible to help us match your citations to DOIs accurately.

References may also be included as an unstructured citation. This option is not as precise as including an already-matched DOI or marking up a citation into individual elements:

<citation key="ref=3">
<unstructured_citation>Clow GD, McKay CP, Simmons Jr. GM, and Wharton RA, Jr. 1988. Climatological observations and predicted sublimation rates at Lake Hoare, Antarctica. Journal of Climate 1:715-728.</unstructured_citation>

Making your references open

All metadata that members register with us is publicly available (open) through our various metadata search and API services. However, references have historically been treated differently from all other metadata.

Our reference distribution policy means that members joining since 1 January 2018 have their references set to open by default, and are included in our full list of members who have opened their references for distribution.

Any member can choose to set their references to open, limited, or closed at any time. The policy can be set differently per DOI prefix.

Reference distribution options

References setting Description
Open Everyone can access your references through our metadata channels, including REST API and UNIXSD query results
Limited Your references can only be accessed by members participating in our Cited-by and Metadata Plus services (this is the default for older accounts)
Closed Your references are only used for our Cited-by service and are not distributed through any of our public Crossref interfaces

If you joined us before January 2018 and want to make your references publicly available (this is recommended), please contact us and we’ll enable reference distribution for your prefix (or prefixes). To enable open references for individual items, you can include a reference_distribution_opt flag within your <journal_article> element, for example: <journal_article publication_type="full_text" reference_distribution_opts="any">

To check if you (or your service provider) are including references in your metadata deposits, you can:

To find out if your references are currently set to open, limited, or closed, you can:

If you need further help, please contact us.

Page owner: Laura J. Wilkinson   |   Last updated 2020-April-08