Bread and pastry and other delicious things

How Baking Works by Paula Figoni. Fantastic and thorough run-down of practical baking science.

Flour Water Salt Yeast, by Ken Forkish, is the one I go back to over and over again to understand the why and how of bread baking. "Why does it react this way?" or "How do I modify this recipe?", the explanations and techniques are something I find very helpful.