http://www.isabelsehbe.com/patanjali-yoga-sutras-book/
Have you read The Yoga Sutras of Patanjali?
I'm thinking of buying a comment about the book?
I read a couple versions and recommend these lectures, if you have time and want to get a description in depth http://acharyadeva-nectar.pbworks.com/The-Yoga-Sutras (the mp3 links are in the bottom of the linked page) Some of the translations on the web are pretty good. It is a relatively short text you do not mind reading on the screen.
Patanjali Yoga Sutras: Three levels of knowledge – impact on society