Animated Performance by Nancy Beiman is just published in its second edition. This is an excellent book from a master animator, one who now teaches at Sheridan College, often regarded as one of the top places in the world to study animation.
Nancy was a supervising animator at DreamWorks and she really knows her stuff. And, as a full-time professor, she knows how to communicate her knowledge.
Any serious animator should have this book on their shelf.
You can buy it here.