Hi Mushashi,
I too can recommend the Kennedy book. It's very thorough and helpful. I went to his satsuki classes but unfortunately he moved way down to the West Country too far for me to go. He's very experienced and knowledgeable.
Another good book is 'Japanese Satsuki Bonsai - How to Grow Satsuki Bonsai and an Introduction to their Varieties'. It is written by Shogo Watanabe. Published in English by Tochinoha Shobou Co Ltd. Mail Address:
info@tochinoha-shobo.com
I expect they would be able to tell you where you could get a copy. Great picture essays - pruning, styling, re-potting etc. Very comprehensive.