Scopus, the Web of Science, and Google Scholar are prime sources for finding cited author references. Other products, however, also offer searching options for finding cited references, including references in both journals and books.
In searching cited authors, the search often depends on the citation style, some standard (Chicago, APA MLA), some in other formats. The Web of Science, for example, has its own format, and the user must enter the search as the database instructions specify.
Searches may retrieve items in a bibliography as well as citations in notes. In some cases the results will include recommendations for further reading or other information unrelated to a cited reference.
To keep citations up to date (and for delivery of topic searches or tables of contents) you may wish to sign up for journal alerts which are available from most databases.