These three videos show you how to search on the Web of Science (WoS), how to interpret the results and sort results by citation counts and how to conduct a 'cited reference search' for an author or article title to gauge its impact.
One of the key databases that allows for citation searching is the Web of Science. Other databases that list citation counts are:
Academic Search Complete (available from Senate House Library)
ERIC (Education Resource Information Centre)
SCOPUS (this is a multidisciplinary database)