Unfortunately, the process of cited reference searching has some pitfalls.
You cannot expect to find all your citations in any one source. Typically, the three main sources, Scopus, Web of Science, and Google Scholar, all provide different results. How different depends on the field and dates of publication. The following articles provide interesting comparisons of Scopus, Web of Science, and Google Scholar:
The databases available for cited reference searching are primarily composed of articles. Books, book chapters, conference proceedings, dissertations and technical reports may be excluded. Although conference proceedings are beginning to be included more often (especially in Scopus), there are fewer places to search for citations of books. Google Scholar does include some books.
Scopus, Web of Science, and Google Scholar each index a finite collection of journals. If an article is cited in a journal not indexed by one of these databases, you will not find that citation when searching them. Some other things to consider regarding database indexing:
- Some journals in various fields may be excluded. Some fields may be more comprehensively covered than others.
- Journal articles in press are not included in the databases.
- Journals are not necessarily consistently indexed nor indexed retrospectively when added to the databases.
- There is limited coverage of non-English publications (Scopus claims to have better coverage than Web of Science).
- Formats such as books are usually not included.
Depending on the year of publication, Web of Science and Scopus may provide vastly different results. Scopus currently provides cited reference searching since 1996, while Web of Science reaches further back. If you are looking for older publications, search accordingly.
While your citation count is important, there are even larger issues to consider.
In
addition to the lack of books and other formats in cited reference
searching databases, these databases do not look at citations on or links from websites. They are not able to indicate how often an article has
been accessed or downloaded from a publisher, website, or institutional
repository. Articles in certain fields may be widely read and cited by users who are not likely to publish (e.g. police departments,
students, city planners, etc.).
An article may be cited because it is bad or coming under question. Simply looking at the citation counts does not give the full picture. Reading the citing article and noting where and how it refers to the cited work can give a better sense of the impact of the cited work.
For more on this topic, see the article Why the Impact Factor of Journals Should Not Be Used for Evaluating Research.
Citation Statistics, a report by the Joint Committee on Quantitative Assessment of Research, identifies a number of ways in which citation data is misused. It reviews the limitations of citation statistics and gives clues on how to best use them. Beware how you use your statistics.