The books are:
- His technical book about exposure is Understanding Exposure
- His composition book is Learning to See Creatively
- His book about digital photography is Understanding Digital Photography
- His book about taking pictures of people is Beyond Portraiture
- I just noticed that he has a new book coming Understanding Shutter Speed
If you don't make much of the technical information in the books you'll surely admire the photos. Nonetheless, the information next to the photos in the books is very inspiring and instructive.