I am hesitant to post this title here because I like to think that anyone who writes a book means well and I would really hate to upset them but someone gave me an old book last week on Tai Chi because they know I do Tai Chi and I do appreciate the sentiment but the book is just plane bad. The postures are bad some of the posture names are not correctly translated and the translation of the I Ching do not appear to be entirely correct either. The book was published in 1974 and I doubt it is still in print but I recommend avoiding it if you want to know about Tai Chi
Tai Chi Ā A Way of Centering & I Ching