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 |
| XML | DOI | XML |
| OAI-PMH oai.crossref.org | prefix, title | 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, although a community-developed plugin is available for OJS. The data from our APIs is delivered in XML or JSON format and needs to be parsed for display on a webpage.
On this page, learn more about:
Using a URL, you can retrieve all citations for a single DOI or prefix within a date range. You will need to provide your Crossref account credentials in the query.
If you use personal, individual user credentials, queries have the following format:
https://doi.crossref.org/servlet/getForwardLinks?usr=email@address.com/role&pwd=password&doi=doi&startDate=YYYY-MM-DD&endDate=YYYY-MM-DD
where:
If you use shared, organization-wide role credentials, queries have the following format:
https://doi.crossref.org/servlet/getForwardLinks?usr=username&pwd=password&doi=doi&startDate=YYYY-MM-DD&endDate=YYYY-MM-DD
where:
On both versions of the query, 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=role&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=role&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 timeouts due to large query results get in touch.
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.
Citations can be retrieved through an XML query. The query contains only the DOI of the cited article stored in the fl_query element. Each XML file must contain only a single DOI.
If you submit a batch query submission with more than one DOI per query, the remaining DOIs in that query will return the message “exceeded limit of forward link queries per submission.” So, any DOIs after the first will not have alerts enabled.
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=ROLE&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>
You can find citations to single DOIs using our admin tool. Log in using your Crossref account credentials, click on the Queries tab, then Cited By Links. This returns a list of DOIs:
For members who manage their journal using OJS v3.1.2.4 or later, you can install a Cited-by plugin from the plugin gallery. It pulls data from the Cited-by API and can display it directly on article webpages. This plugin has been generously contributed by the community and is not maintained by Crossref.
If you are not using OJS but use another third party software to manage your journal there is a good chance that there is also a plugin available. We don’t maintain a comprehensive list of Cited-by plugins, but you can contact your software provider for details.
Note that the OAI-PMH API returns matches for the following article types: Journals, Books, Book Series, and Components. Other types are not included. To get complete results, we recommend using the HTTPS POST or an XML query (see the two sections above) for retrieving Cited-by matches rather than 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=role&pwd=password&set=record type:prefix:pubID&from=YYYY-MM-DD&until=YYYY-MM-DD&metadataPrefix=cr_citedby&include_postedcontent=false
where:
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 our 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 the DOI of each citation. You can use our REST API or XML API to retrieve the full bibliographic data for each citation.
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.
Sometimes citations don’t show up in Cited-by when you would expect them. There could be several reasons for this:
Note that citations are only retrieved from works with a Crossref DOI and will differ from citation counts provided by other services. Not all scholarly publications are registered with us and not all publishers opt to deposit references, so we can’t claim that citation counts are comprehensive.
If you have difficulty accessing citation matches for your own content, try checking first with the admin tool and see if you can replicate the results there using one of the API options above.