Mike Caro is one of the forerunners when it comes to poker strategy. He has authored many reports and published many articles on the same over the years. So when he writes a book about poker tells, we need to sit up and take notice.
The Body Language of Poker talks about poker tells like facial movements, physical movements, voice inflections, posture, eye movement, breathing, etc. He wrote the original book in 1994, which was updated 10 years later with more examples and information, courtesy of further research. The book was very ahead and a first for its time, and that added to its immense popularity. This can be called as a classic, and is the best book to refer to for poker tells and how to identify them.