Gordon Muirs book Yang Style Traditional Long Form T'ai Chi Ch'uan: As Taught by Master T. T. Liang is now available for purchase online and through your local bookstore. 

Amazon

.The book features a detailed look at the physical mechanics of performing good T'ai Chi. The book is divided into three separate sections including:

1. Writings of Master T. T. Liang
2. Foundation training
3. Yang Style Traditional Long Form posture details

At 225 pages the book is full of interesting training drills, anecdotes from the master and a very detailed look at form performance.