[tP5n]

Mostly everything Phil Gordon, David Sklansky and Ed Miller put out over the years. poker differs a lot in its variants, atleast to newcomers, so it's probably best to pick up one variant (no limit hold'em I'm looking at you) and start from there.

[mcgin]

+1 for sklanskys stuff, particularly his Theory of Poker book

[sokoloff]

His "Fundamental Theorem of Poker" was mind-blowing to me when I first read it.

I like most of what he's written, so just to whet some appetites, I'll link to the FToP overview: https://en.wikipedia.org/wiki/Fundamental_theorem_of_poker