Once you have identified some of the key research you are interested in, you will want to keep up to date with how that research is treated or used by other researchers. Citation searching is the process of searching for and identifying subsequent research which cited the original article which you have already identified.
Citation searching: Having found publication X, the process of searching for publications which have since cited publication X.
Many publisher and subject databases offer some limited option to view which articles they provide access to which have cited a particular paper, but to conduct an effective citation search you need to be able to search a comprehensive, multi-disciplinary range of publications. There are four key sources which allow you to do this.
Citation data are not usually freely available to access, they are often subject to inconsistent, hard-to-parse licenses, and they are usually not machine-readable. An international collaboration between scholarly publishers and society's, researchers and other interested parties are working together to enable the unrestricted access to scholarly citation data.
As a result of this collaboration, since 2017 many subscription-access and open-access publishers have made the decision to release reference list metadata publicly. These include: American Geophysical Union; Association for Computing Machinery; BMJ; Cambridge University Press; Cold Spring Harbor Laboratory Press; EMBO Press; Royal Society of Chemistry; SAGE Publishing; Springer Nature; Taylor & Francis, and Wiley. A complete list of participating publishers and publishing organisations can be found here.
By June 2017, the fraction of publications with open references has grown from 1% (prior to the collaboration) to more than 45% out of the nearly 35 million articles with references deposited with Crossref (to date). This citation data from Crossref is then available for use by researchers or through other services, such as Durham University's Library Discover service (as shown in the image above).
Web of Science of is multi-disciplinary bibliographic database which indexes over 11,000 journals, as well as smaller citation indexes of monographs, books and conference papers. As well as identifying citations to a research paper you have found, it will also allow you to set-up a citation alert notifying you if anything is subsequently published which cites the paper you have already identified.
Did you know? Citation data from the Web of Science is used to calculate widely used metrics such as the Jounral Impact Factor (JIF). Check out our pages on bibliometrics for more information.
You can access guidance on how to conduct a citation search on Web of Science via their support pages.
Scopus, like Web of Science, is a multidisplinary database indexing over 19,000 journals and other materials. It will, like Web of Science, allow you to identify citing papers, and set up an alert for subsequent papers indexed in Scopus which cite the paper you are interested in.
Did you know? Citation data from Scopus was used by some Units of Assessment in REF2014, and is used in various international university rankings such as the QS World University Rankings, and the THE University Rankings. See our bibliometrics pages for further information.
You can access online guidance for using Scopus, including a tutorial for searching for cited references, via their support web pages.
Google Scholar also allows you to identify if a publication has been cited. Below articles title in the results list, it will include the number of citing publications identified within Google Scholar's index (and a link to citations as found in Clarivate Analytics Web of Science database).
Note that the citing documents found will include citations from sources not found via other services (Scopus, Web of Science), such as citations in preprints, technical reports and theses & dissertations. It may also include duplicated citations - inflating the number of "real" citations reported. See our blog post for further detail on citations in Google Scholar.
You can also, after clicking on the link to see all citing articles, set up an email alert if anything subsequently cites the publication.