Old Edition (1940s) of the American National Biography (available through Internet Archive)
These are older editions, so will not necessarily be helpful for post 1940s individuals, but, in the case of your class, these entries can still hold a good deal of helpful first pass information. You can likely find other resources that will be more up to date, but these can give you a start and a basic overview. They are in no good order in Internet Archive, so you'll have to look into each one to find what letters are covered.
