The following three databases cover many different subjects, but none in great depth. Very good for retrieving materials from other disciplines.
Web of Science provides ways to find out how many times an article has been cited. Caveat: Much stronger in the sciences than in the social sciences.
Basic Search: Enter a topic, e.g., "vocational rehabilitation", sort results by 'Times Cited,' and then use the limits on the left, e.g., 'PUBLIC, ENVIRONMENTAL & OCCUPATIONAL HEALTH.'
Cited Reference Search: Select to find articles citing a noted author and/or article.