Zachary Elwood's Reading Poker Tells, published in 2012, is widely considered to be the best book on the subject of poker tells. It's the first book in his poker behavior trilogy.
This book will teach you how a professional poker player analyzes the facial expressions, body posture, physical gestures, and verbal statements of opponents in a live poker setting. Besides cataloging the most meaningful behavior, this book also gives a mental framework for thinking about and remembering poker tells. It also contains other tips on general poker psychology, including methods of deceiving and manipulating opponents, and methods for becoming "unreadable".