I wrote Expert Heads Up No Limit Hold’em, a two volume work motivated by the desire to make the fundamentals of game theory accessible and useful to poker players. The focus is on heads up (i.e. two-player) play, because that’s my specialty, and it’s where a lot of the theory is most useful, but a lot of the ideas covered apply to any form of poker.
I like to think it differentiates itself from other works in the field by being rigorous enough that readers should come away with the ability to analyze new situations from first principles, while staying focused what’s most important – how to make more money in real games.
More recently, I contributed a chapter to Excelling at No-Limit Hold’em, edited by Jonathan Little.
I’ve also produced a couple video series. The first covers a variety of extra topics supplemental to the books. See D&B Poker or HUSNG.com for more info. The second walks players through the design and implementation in iPython of software to solve for equilibria of model poker games. It’s easy, I promise(!), and a few hours of sample content are on youtube. Check it out at HUSNG.com or D&B Poker.