In Yoga: The spirit and practice of moving into stillness, by Erich Schiffmann, one finds incredibly detailed description of each asana, describing how to align each part of your body, and how to move slowly into various variations. Schiffmann also provides good descriptions of breath techniques, and a beautiful, inspiring take on how you may feel as you grow in your yoga practice.
This was my favorite book from the extensive list of required reading when I did my teaching certification program. (I was lucky enough to find it at a used bookstore on Franklin Street!) I loved the chapters describing asanas – very thorough for learning.
FOR MORE Check out the author, Erich Schiffman’s, website. His favorite links, for some more great resources, are here: http://www.movingintostillness.com/links.html
See if it’s at a library near you! Or for a tree-free, mileage-free option, it’s available for the kindle.
It has been around awhile, so if you’d like your own physical copy, you can probably Find a used copy of the book.
Schiffmann, Erich. Yoga: the spirit and practice of moving into stillness. New York: Pocket Books, 1996.