P Chem - group theory?

We're doing group theory in my graduate physics cl. I haven't taken chemistry since high school, and I'm having trouble figuring out the symmetries of various molecules. Can anyone recommend a good reference book? Any good P Chem book that covers group theory well? The textbook for my cl only covers it very briefly, but there are hundreds of P Chem books in our library - I just need a good place to start.