How can I find who has cited an article?
Google Scholar includes a link, "Cited by #", underneath the article in your search results.
If you are looking for articles that have cited a specific article you might find it easier to search for that article using Google Scholar's advanced search features. Look for a link to advanced search right next to the search box.
And it is a good idea to link to Google Scholar from a library web page so that you will see the Find @ UNC links that lead you to journal subscriptions.
Web of Science (ISI) also includes links to articles that cite the articles you see in search results.
You can link to Google Scholar or Web of Science from the HSL home page: http://www.hsl.unc.edu/
Look in the right hand column in the Quick Resources section.