Also
Jenkin's Spoiler-Laden Guide to Asimov has a summary of many short stories:
http://homepage.mac.com/jhjenkins/As...habetical.html
Oops. I posted again before refreshing the page and seeing your post.
Locus magazine online has a database of magazines and contents. Also which anthologies contain the story.
http://www.locusmag.com/index/0start.htm#TOC