Ms. Baron's Website
www.aslpro.com
aslbrowser.commtechlab.msu.edu (click "browser", then "dictionary")
www.gallaudet.edu (click on: "Clerc Center" has a lot of info)
www.asd-1817.org (ASL Historical info, museum, Deaf Education)
There are other valid websites to use. These are just a few I have used and liked.
No Wikipedia! ~look at wikipedia bibliographies at bottom of page, and follow to link to find the sources.