Crystals, X-rays and Proteins: Comprehensive Protein Crystallography Revised ed. Edition

To cut a long story short : If you want to understand the physical principles of single crystal X-ray diffraction and you come from a biology/chemistry background this is the first book you definitely want to read. It will slowly and gently give you the mathematics you need, and will carefully use them to develop the theory. This is not a how-to type of book. Its aim is to make you understand single crystal X-ray diffraction and not to guide through the actual practical implementation of the ideas.This is one of the best crystallography books ever written, and it is with pleasure that I wholeheartedly recommend it.

This is the most underrated book ever. If you're familiar with fundamental molecular biology and have just a brief understanding of high-school mathematics/physics, this book is the best place to start. Hats off to the authors!