Bonsai With American Trees by Masakuni Kawasumi (1984, Paperback)

I own several books on Bonsai. This book has much more information than the others I've bought. It hit on key topics that other books never even mentioned, like the fact that all Bonsai (with the exception of miniatures) should be kept outdoors even through the freezing winter. The book explains why keeping them indoors year-round will eventually kill them.
This is a fantastic book for anyone who wants to learn anything about Bonsai.