I found this book very helpful for my particular situation--I have health issues preventing me from doing much standing and/or movement right now. I'm starting my energy practice, literally, from the ground up and I've found the seated chi kung exercises to be most helpful.

This book describes the sitting qigong exercises, but it doesn't provide good explanations why you should be doing them and it doesn't describe benefits of each exercise.
I found it boring and not very useful. The only thing that I liked is that he gave a good detailed explanation of opening and closing sequence you should do before and after every qigong practice.