The main resources for tracking citations are the Web of Science and Scopus databases. The University of Sussex Library has an institutional subscription to both Web of Science and Scopus. They can be accessed from the Library's Online Resources A-Z list.
Scopus provides the abstracts and cited references of over 25,000 peer-reviewed titles from more than 5,000 international publishers in the sciences, social sciences and the arts and humanities. It includes references of all articles published since 1996, offering newly-linked citations across the widest body of articles available including Open Access and online-only titles.
Web of Science provides access to the Science Citation Index, Social Sciences Citation Index and Arts & Humanities Citation Index. It gives citation information for approximately 21,000 journals.
Web of Science is integrated with a resource called Journal Citation Reports (JCR). The JCR compiles citation data and has been considered the definitive source of traditional publication metrics for some time. Scopus has developed it's own metrics and tools for analysis, which pose a challenge to the JCR. Both sources can provide valuable information if used responsibly.
Different citation tracking tools work with slightly different datasets. This means that there will often be discrepancies from one data source to the next, when it comes to citation counts. While citation tracking tools can provide valuable insight, it should be noted that no single source can create a complete picture of all possible citations.
Google Scholar citation data will often show a much higher citation count. This is because Google Scholar looks at a wider range of publications, including grey literature, monographs and theses, so it may count citations that are not picked up by other tools. However, Google Scholar counts may also include duplicate records, misattributions and discrepancies and may be problematic.