Start with high-confidence body language books, then narrow by subgenre or adjacent topics.
Phil Hellmuth Presents Read 'em and Reap
Joe Navarro, Marvin Karlins
What Every BODY Is Saying
The Dictionary of Body Language
Joe Navarro
The Definitive Book of Body Language
Barbara Pease, Allan Pease
Caro's Book of Poker Tells
Mike Caro
