What book should I read next?

I just got finished up with the summer session at school and have a couple weeks before I have to start back for fall. I want to read 2 books during this time.

Here is what I have read:
Super System
Super System 2
Harrington on Holdem
Play poker like the Pros
Small Stakes Holdem

I was thinking about Theory of Poker or the 3rd edition of Winning Low Limit Holdem.

Thanks for your suggestions.