Overlap between different services providing citation data

Hello - I’m looking for an open source of data for the number of citations and so am very excited to use Crossref. I’m curious if there is data somewhere that shows the number or fraction of publishers/journals/papers in Crossref that include reference data. When I spot check various dois at Crossref, google scholar, Web of Science, I see some variation. I sense google scholar would be inflated since they are counting citations for things that wouldn’t have doi’s, but what should we expect the overlap be between Crossref and google scholar?

Also, am I right that individual researchers can only get the number of citations a paper receives and not the actual doi’s for the cited papers?


Hi @pschloss,

Thanks for your message, and welcome to the community forum. Glad you found us and are finding our metadata useful!

First off, we don’t have a formal relationship with Google.

We do find that Crossref DOIs and metadata are indexed by Google’s crawlers and appear in search engine results but as their approach isn’t public, we don’t have any insight into their processes or timelines unfortunately.

We do know that our REST API is open to all, so it may be part of their process.

As for your question about reference metadata, our REST API is a great place to get this information:

Which members are registering references and how many DOIs have references registered (by member): http://0-api-crossref-org.lib.rivier.edu/works?filter=has-references:true&facet=publisher-name:*&rows=0&mailto=support@crossref.org

Comparatively, which members are NOT registering references and how many DOIs have no references registered (by member): https://0-api-crossref-org.lib.rivier.edu/works?filter=has-references:false&facet=publisher-name:*&rows=0&mailto=support@crossref.org

Also, am I right that individual researchers can only get the number of citations a paper receives and not the actual doi’s for the cited papers?

Yes, that’s correct. The cited-by counts are available in the REST API. Look for the is-referenced-by-count in the JSON output; that tells you how many other Crossref DOIs have cited the DOI in question. For instance, this DOI: https://0-api-crossref-org.lib.rivier.edu/works/10.1016/j.bioactmat.2020.11.006?mailto=support@crossref.org has been cited by 80 other Crossref DOIs. You’ll also see that DOI 10.1016/j.bioactmat.2020.11.006 has a references-count of 57. That means that this DOI has 57 references in its metadata record.

But, the details of which DOIs are citing the DOI in question is only available to our members for their own DOIs.

Please let me know if you have any additional questions,

Thanks, this is very helpful!

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The is-referenced-by-count is very useful, but sometimes I require more flexibility of the REST API.

Are there any plans to make the cited-by DOI’s available from the CrossRef (REST) API for non-members i.e. the general public, like myself? If not why not? The data is available in CrossRef.

  • It allows an author to track their citations over time in general and of a specific article (DOI) in particular. Now it is only possible in e.g. Clarivate’s Web of Science (not open).
  • Following citations to a particular article DOI allows a (bibliometric) researcher to spot e.g. potential trends per journal, per research area, affiliation etc.