My favorite reference books

The two reference books that I love using and that I find I am constantly refering users to are:

American National Biography

If a student needs a bio of a (dead) American, I often send them to this sprawling set. Not only are the entries well-written (they are often composed by the leading biographer for that person), they are of a sufficient length to lend depth (a longish essay) but not so much so that the reader is overwhelmed and they usually feature excellent bibliographies.

Encyclopedia of New York City

I once foolishly believed I could read this thing from A-Z (I have my own copy at home). I've found this is a great source for journalism students who are doing neighborhood stories and need background info, as well as for the obvious history assignments.