The Crossref Curriculum

Retrieve citations using Cited-by

There are a number of methods through which to retrieve citations:

Input Query for Output
Admin tool DOI List of citing DOIs
HTTPS doi.crossref.org DOI, prefix XML
OAI-PMH oai.crossref.org prefix, title XML
XML DOI XML

There are two additional options to receive a “push” notification any time one of your deposited works is cited:

Input Output
Email notification Email sent to an address provided by the member
Notification callback Sent to an HTTP(S) URL endpoint hosted by the member

Note that we don’t provide a plugin to directly display Cited-by results on a publisher website. The data is delivered in XML format only and needs to be correctly reformatted.

On this page, learn more about:

Retrieve citation matches using HTTPS POST

Using a URL, you can retrieve all citations for a single DOI or prefix within a date range. Queries have the format:

https://doi.crossref.org/servlet/getForwardLinks?usr=username&pwd=password&doi=doi&startDate=YYYY-MM-DD&endDate=YYYY-MM-DD

where:

  • username and password are the Crossref admin tool username and password for the prefix or title being retrieved;
  • doi can be a full DOI or a prefix.

A date range is optional. Dates in the query refer to when the citation match was made (usually shortly after the DOI of the citing article was registered), not the publication date of the articles being queried for: all citations found in the given period will be returned, regardless of when the cited articles were originally deposited. Queries can also be made for a single day, in which case use the following format:

https://doi.crossref.org/servlet/getForwardLinks?usr=username&pwd=password&doi=prefix&date=YYYY-MM-DD

By default, citations from posted content (including preprints) are not included. To retrieve them as well, include &include_postedcontent=true in the query URL:

https://doi.crossref.org/servlet/getForwardLinks?usr=username&pwd=password&doi=prefix&date=YYYY-MM-DD&include_postedcontent=true

Output is XML formatted according to Crossref’s query schema.

If the query times out, we recommend using a smaller query, for example by using a narrower date range or splitting prefixes into individual DOIs. This is unlikely to affect most users, however if you frequently experience very large queries please contact us.

Here is some example output:

<crossref_result xmlns="http://www.crossref.org/qrschema/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xsi:schemaLocation="http://www.crossref.org/qrschema/2.0 http://www.crossref.org/qrschema/crossref_query_output2.0.xsd">
<query_result>
<head>
<email_address>none</email_address>
<doi_batch_id>none</doi_batch_id>
</head>
<body>
</forward_link>
<forward_link doi="10.1021/jacs.9b09811">
<journal_cite fl_count="0">
<issn type="print">2161-1653</issn>
<issn type="electronic">2161-1653</issn>
<journal_title>ACS Macro Letters</journal_title>
<journal_abbreviation>ACS Macro Lett.</journal_abbreviation>
<article_title>Critical Role of Ion Exchange Conditions on the Properties of Network Ionic Polymers</article_title>
<contributors>
<contributor first-author="true" sequence="first" contributor_role="author">
<given_name>Naisong</given_name>
<surname>Shan</surname>
</contributor>
<contributor first-author="false" sequence="additional" contributor_role="author">
<given_name>Chengtian</given_name>
<surname>Shen</surname>
</contributor>
<contributor first-author="false" sequence="additional" contributor_role="author">
<given_name>Christopher M.</given_name>
<surname>Evans</surname>
</contributor>
</contributors>
<volume>9</volume>
<issue>12</issue>
<first_page>1718</first_page>
<year>2020</year>
<publication_type>full_text</publication_type>
<doi type="journal_article">10.1021/acsmacrolett.0c00678</doi>
</journal_cite>
</forward_link>
</body>
</query_result>
</crossref_result>

Note that the fl_count property gives the number of times the citing article has itself been cited.

Retrieve citation matches using OAI-PMH

This format retrieves Cited-by matches established within a date range for a prefix or title. Queries have the following format:

https://oai.crossref.org/OAIHandler?verb=ListRecords&usr=username&pwd=password&set=J:prefix:pubID&from=YYYY-MM-DD&until=YYYY-MM-DD&metadataPrefix=cr_citedby&include_postedcontent=false

where:

  • username and password are the Crossref admin tool username and password for the prefix or title being retrieved;
  • content type is J for journal; B for books, conference proceedings, datasets, reports, standards, or dissertations; and S for series;
  • prefix is the owning prefix of the title being retrieved;
  • pubID is the publication identification number of the title. This is optional: to query for all titles related to a prefix, simply omit the pubID;
  • metadataPrefix=cr_citedby indicates that the results should include Cited-by matches rather than item metadata.

A date range is optional. Dates used refer to when the citing articles were last updated, not the publication date of the articles being queried for. All citations found in the given period will be returned, regardless of when the cited articles were originally deposited.

By default, citations from posted content (including preprints) are not included. To retrieve them as well, add &include_postedcontent=true to the query URL.

Output is XML formatted according to Crossref’s query schema and contains a list of the DOIs that cited the specified article or prefix.

Some OAI-PMH requests are too big to be retrieved in a single transaction. If a given response contains a resumption token, the user must make an additional request to retrieve the rest of the data. Learn more about resumption tokens, and OAI-PMH requests.

An example OAI-PMH query response is as follows:

<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2020-12-21T10:38:26</responseDate>
  <request verb="ListRecords" from="2020-01-01" until="2020-01-02" set="J:10.1021" metadataPrefix="CR_CITEDBY" resumptionToken="78da6164be33c5fb" >http://oai.crossref.org/oai</request>
  <!-- recipient 1234 abc -->
  <ListRecords>
    <record>
      <header>
        <identifier>info:doi/10.1016/1044-0305(94)80016-2</identifier>
        <datestamp>2020-12-18</datestamp> <setSpec>J:10.1021</setSpec>
      </header>
      <metadata>
          <citations>
           <citation xmlns="http://www.crossref.org/schema/crossref_citations_1.0.0">
          <doi>10.1023/1051-030580416</doi>
            <citations-cited-by>
              <doi type="journal-article">10.1021/acs.jproteome.0c00464</doi>
              <doi type="conference-paper">10.1007/978-1-0716-0943-9_16</doi>
              <doi type="journal-article">10.1038/s41598-020-78800-6</doi>
              <doi type="posted-content">10.1101/2020.12.01.407270</doi>
              <doi type="journal-article">10.1007/s11120-020-00803-1</doi>
          <citations-cited-by>
          </citation>
        </citations>
      </metadata>
    </record>
    <resumptionToken >78da6164be33c5fb</resumptionToken>
  </ListRecords>
</OAI-PMH>

OAI-PMH queries return only the DOI of each citation. You can use our REST API or XML API to retrieve the full bibliographic data for each citation.

Retrieve citation matches using an XML query

Citations can also be retrieved through an XML query. The query contains only the DOI of the cited article stored in the fl_query element. For best results, each XML file should contain a single DOI.

Setting the alert attribute to “true” instructs the system to remember this query and to send new Cited-by link results to the specified email address when they occur. Note that an email address cannot be unset from receiving notifications, so only use this option for email addresses that will continue to receive notifications on a long-term basis.

Here is an example XML query:

https://doi.crossref.org/servlet/query?usr=USERNAME&pwd=PASSWORD&qdata=<?xml version="1.0"?>
<query_batch version="2.0" xmlns = "http://www.crossref.org/qschema/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.crossref.org/qschema/2.0 http://www.crossref.org/qschema/crossref_query_input2.0.xsd">
    <head>
        <email_address>EMAIL</email_address>
        <doi_batch_id>fl_001</doi_batch_id>
    </head>
    <body>
        <fl_query alert="false">
            <doi>10.1021/acs.joc.7b01326</doi>
        </fl_query>
    </body>
</query_batch>

By default, citations from posted content (including preprints) are not included. To retrieve them as well, use <fl_query include_postedcontent="true"> in the body of the query.

Here is an example of the output XML:

<crossref_result xmlns="http://www.crossref.org/qrschema/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xsi:schemaLocation="http://www.crossref.org/qrschema/2.0 http://www.crossref.org/qrschema/crossref_query_output2.0.xsd">
  <query_result>
    <head>
      <email_address>{email}</email_address>
      <doi_batch_id>fl_001</doi_batch_id>
    </head>
    <body>
      <forward_link doi="10.5555/ums71316">
        <journal_cite fl_count="0">
          <issn type="print">1070-3632</issn>
          <issn type="electronic">1608-3350</issn>
          <journal_title>Russian Journal of General Chemistry</journal_title>
          <journal_abbreviation>Russ J Gen Chem</journal_abbreviation>
          <article_title>Simultaneous Formation of Cage and Spirane Pentaalkoxyphosphoranes in Reaction of 5,5-Dimethyl-2-(2-oxo-1,2-diphenylethoxy)-1,3,2-dioxaphosphorinane with Hexafluoroacetone</article_title>
          <contributors>
            <contributor first-author="true" sequence="first" contributor_role="author">
              <given_name>V. F.</given_name>
              <surname>Mironov</surname>
            </contributor>
            <contributor first-author="false" sequence="additional" contributor_role="author">
              <given_name>M. N.</given_name>
              <surname>Dimukhametov</surname>
            </contributor>
            <contributor first-author="false" sequence="additional" contributor_role="author">
              <given_name>Ya. S.</given_name>
              <surname>Blinova</surname>
            </contributor>
            <contributor first-author="false" sequence="additional" contributor_role="author">
              <given_name>F. Kh.</given_name>
              <surname>Karataeva</surname>
            </contributor>
          </contributors>
          <volume>90</volume>
          <issue>11</issue>
          <first_page>2080</first_page>
          <year>2020</year>
          <publication_type>full_text</publication_type>
          <doi type="journal_article">10.1134/S1070363220110109</doi>
        </journal_cite>
      </forward_link>
    </body>
  </query_result>
</crossref_result>

Retrieve citation matches using the admin tool

Once you have Cited-by enabled, you can find citations to single DOIs using the Crossref admin tool. Log in, click on the Queries tab, then Cited By Links. This returns a list of DOIs:

Cited-by view in the admin tool

Citation notifications

You can receive citation notifications by email or an endpoint notification. In both cases the text of the message is the same: it contains the same output as an XML query, containing details of the citing and cited works.

To select an email address for Cited-by notifications, see the XML query section.

Troubleshooting Cited-by queries

Sometimes citations don’t show up in Cited-by when you would expect them. There could be several reasons for this:

  • The references haven’t been included in the metadata. We don’t use article PDFs or crawl websites to retrieve references, we rely on them being deposited as metadata by our members. You can use our APIs to check whether references are present.
  • The DOI of the cited work wasn’t included in the reference and there was either an error in the metadata or insufficient information for us to make a reliable match. In this case, check the metadata for any errors and contact the owner of the citing work to redeposit the references.
  • If the citing article was registered very recently it can take time to update the cited article’s metadata. If this happens, wait for a few days before trying again.

Note that citations are only retrieved from works registered with a Crossref DOI and will differ from citation counts provided by other services. Not all scholarly publications are registered with Crossref and not all publishers opt to deposit references, so we can’t claim that citation counts are comprehensive.

If you can’t access citation matches for a journal you own:

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