Can someone recommend some poker strategy books that will introduce me to the more mathematical aspect of the game?

I've been playing a lot in the past few months, but I feel that the competition I have been facing is not teaching me much.

Small Stakes Hold Em by Sklanksy is pretty much the bible around here. It's more for Limit, but it's good to read even if you're playing NL. I hear Theory of Poker is also good.

Harrington on Hold Em is good for NLHE Tournaments.

Most people like the SuperSystem books. I've read most of the second, and it was decent. It covers a variety of games.

Finally, I hear good things about Ed Miller's books.