This book contains an extensive analysis of the use of mandalas in personal psychospiritual development or as a tool in expressive arts therapy. If you're interested in these topics, you may find it useful. It's accessible whether you're trained in these topics already, or not. In fact, the author's suggestion of drawing a mandala daily or weekly, as a practice, and her suggested ways looking at the resulting series, are particularly interesting.
Unfortunately, I found the discussions of symbolism to lack cultural sensitivity, particularly in the tendency to associate "dark" and "black" primarily with negative aspects of the personality and "white" and "light" with positive aspects of personal and spiritual growth. This book was written in the 1990s, so I don't feel comfortable excusing the author on the grounds that consciousness about these issues hadn't been raised yet. Instead, I keep thinking she should have known better. But I haven't found a better book on mandala work yet. Be sure I'll post it if I do.