Any good beginner books on Unix

I'm getting into Unix through the terminal application on my Mac. I'm using the Mac OS X missing manual and am about to finish the chapter on Unix. Anyone have a good book they can recommend on beginning Unix?

Introductory/ Beginner unix book

I'm learning Unix through the terminal application. I posted this request before, but no answer so I'm trying again. I'd really like to learn Unix, but I'm confused. There are different versions and I'm not sure what beginner book I need to start -- my Mac has Darwin which as you know is a fork of BSD Unix. Is there any book on Darwin I could get, or would a book on Unix in general do just as well? Any do you know any specific titles?

NOTE: Merged crossposts

Unix in a Nutshell and Unix for Dummies worked for me. For AIX specific stuff try rootvg.net. There is a decent list of "Apple Unix" commands here: OS X commands
-Dave