Theory of Poker definately
Hold'em for Advance Players as you move up in limits (or so I've been told. Apparently some of the more advanced plays are less useful against fish.)

As as supplement to SSHE, I'd read Weighing the Odds in Hold'em by Yao. The first 100 pages are review, but his later chapters, and short handed stuff are great!

If you're playing B&M I'd also read Caro's book of tells.