Cited references are the articles, books or other materials listed in a bibliography or as works cited in a particular publication. Because citation databases index each reference, it is possible to search these cited references. One can follow a particular cited reference, or cited author, forward in time to find more current articles that have also cited that author or work.
Impact factor for journal X= The number of citations in a given year, to all articles published in journal X for the previous two years, divided by the number of articles in that journal for those previous two years.
Cited reference searching is included in the following:
Scopus (all disciplines; comprehensive)
Google Scholar (all disciplines; comprehensive)
Academic Search Complete (all disciplines)
Cited references for Books