Crossref Cited-by

Crossref Cited-by
Name	Crossref Cited-by
Type	Citation linking service
Owner	Crossref
Launched	2008
Website	Crossref

Crossref Cited-by is a citation-linking service provided by Crossref that enables publishers, researchers, and platforms to discover and display links from a scholarly work to subsequent citing works. The service aggregates citation metadata to show which journal articles, books, conference proceedings, and reports cite a given work, integrating with publisher platforms, indexing services, and institutional repositories. It plays a role in scholarly infrastructure alongside entities such as Digital Object Identifier, ORCID, DataCite, CrossRef.

Overview

Crossref Cited-by provides machine-readable citation relationships that connect a source item to items that cite it, supporting discovery on publisher websites, scholarly portals, and bibliometric tools. The service interoperates with standards and initiatives including Digital Object Identifier, ORCID, DOAJ, SCImago Journal Rank, PubMed Central, CrossRef Cited-by-adjacent services, and complements resources like Scopus, Web of Science, Google Scholar, Dimensions (database). It returns metadata fields such as citing DOI, publication title, authorship, publication date, and the context of citation when available, enabling downstream displays and analytics used by institutions such as Harvard University, University of Oxford, National Institutes of Health, Wellcome Trust.

History and Development

The service emerged as part of Crossref’s efforts to enhance scholarly linking and metadata services in the 2000s, building on earlier DOI infrastructure championed by International DOI Foundation and widespread adoption by publishers including Elsevier, Springer Nature, Wiley-Blackwell, Taylor & Francis. Early collaborations drew on citation-extraction research from projects associated with PubMed, arXiv, and initiatives supported by funders such as Bill & Melinda Gates Foundation and National Science Foundation. Over time the product evolved with partnerships involving DataCite, integration with registry efforts like ORCID and coordination with standards from CrossRef Metadata Schema Committee and adopters across institutions like MIT, Stanford University, and University of Cambridge.

Data Sources and Coverage

Data powering the service derives primarily from Crossref member deposits submitted by publishers, societies, and repositories including PLOS, BMJ Group, IEEE, American Chemical Society, and American Physical Society. Supplementary inputs originate from indexing partners and text-mining initiatives similar to those used by PubMed Central and arXiv. Coverage varies by discipline and publisher participation, with stronger representation for journals from major houses such as Elsevier, Springer Nature, and Wiley, and evolving inclusion for monographs and conference proceedings from organizations like ACM and Institute of Electrical and Electronics Engineers. Geographic and linguistic coverage reflects participation from institutions in regions including United States, United Kingdom, China, Germany, and India.

Technical Implementation and APIs

The service exposes APIs and metadata feeds that use RESTful patterns and JSON, aligning with Crossref’s broader API ecosystem and metadata schema used by services such as ORCID, DataCite, and OpenAIRE. Implementations commonly use HTTP, persistent identifiers like Digital Object Identifier, and schema fields interoperable with Schema.org and library standards adopted by Library of Congress and OCLC. Publishers implement Cited-by displays through APIs integrated with content platforms provided by vendors such as HighWire Press, Silverchair, and Atypon. Developers and institutions often combine the Cited-by API with bibliometric tools like VOSviewer and CiteSpace for network visualization and analysis.

Use Cases and Impact

Cited-by data supports discovery features on article pages, altmetrics displays used by services like Altmetric (company), research evaluation at universities including University College London and Imperial College London, literature reviews by researchers at organizations such as Max Planck Society, and tracking of scholarly influence for funders like Wellcome Trust and European Research Council. Integration with institutional repositories and library systems at organizations such as California Digital Library enables enriched metadata services. The availability of citation links has influenced practices in tenure and promotion committees at universities like Columbia University and Yale University and informed policy reports produced by entities such as UNESCO.

Access, Licensing, and Costs

Access to Cited-by metadata is governed by Crossref membership and licensing policies, with tiers for members and metadata consumers that mirror the broader Crossref governance model involving publishers like IEEE, Springer Nature, and Elsevier. Some functionalities are available openly to non-members while enriched services and bulk access may require agreements or membership, similar to how access has historically been structured by organizations such as Clarivate and Elsevier for proprietary citation indices. Funders and consortia, including Coalition S and national library consortia in Canada and Australia, negotiate access patterns aligned with open infrastructure principles advocated by groups like SPARC.

Criticisms and Limitations

Critiques of the service mirror broader concerns in citation infrastructures: incomplete coverage due to voluntary publisher deposit practices affecting representation for smaller publishers and regional journals such as those in Latin America and Africa, uneven linking for disciplines with monograph-dominated citing patterns like those common at University of Chicago Press and limitations in capturing citation context compared with full-text citation-indexing initiatives at PubMed Central or proprietary offerings by Clarivate Analytics. Scholars and librarians in institutions including Princeton University and University of Toronto have noted issues with latency, metadata quality, and dependence on publisher-supplied metadata, raising debates also engaged by Scholarly Publishing and Academic Resources Coalition and policy makers in European Commission.

Category:Citation indexing