How do I find out how many times an article has been cited?

The number of times an article has been cited in the published literature is measured by several major databases including: Web of Science, Google Scholar, SciFinder-n, PsycINFO, Citeseer.

Each of those databases only count citations for the journals that it indexes. When looking up the number of times an article has been cited, it is important to understand that the citation counts can be different depending on which database is used. It is best to look up citation counts in several different databases (e.g., look up the number of citations to an article using Google Scholar and Web of Science) to gauge the possible range of citations counts for a particular article.