NL Poker- Opinions wanted!

[Nookx]

Hey, My friend wanted to start playing nl poker at the 6 max 25 dollar nl ring games. I wanted to recommend him to 3-5 books that would help him get started as well as take him to the most advanced level you can obtain merely through reading books. What 3-5 books would you reccomend he get? I have read a few poker books but not many of 2+2's publications, so im just not sure what would be best. Thanks Ahead of time.