Works Cited:

Giorgi, Gianfranco. Simon & Schuster’s Guide to Bonsai. Ed. Victoria Jahn. New York: Simon & Schuster, 1990.

This book gives very clear and simple introductions to the history, art, and biology of bonsai. Two-thirds of the book is dedicated to evaluations of different species used as bonsai: photos of each and descriptions of their growth habits, repotting/pruning requirements, and whether they can be used as indoor or outdoor bonsai. This is very helpful.

Koreshoff, Deborah R. Bonsai: Its Art, Science, History, and Philosophy. Portland, Oregon: Timber Press, Inc., 1997.

An absolutely wonderful book - I plan to buy a copy for myself soon. Her writing is very thorough, her pictures clear, and her instructions illustrated with very helpful drawings. She covers all imaginable topics about bonsai, and does so in enough depth to help an intermediate or even advanced bonsai hobbyist.

Stowell, Jerald P. The Beginner’s Guide to American Bonsai. New York: Kodansha International, 1998.

The instructions are thorough, yet brief, so it's a very good first book. The drawings are helpful and the photo gallery in the middle is beautiful. However, this book was first published in 1978, and in some cases shows its age, recommending a few treatments that are not  suggested for tree care today. (In a bonsai, these practices shouldn't be a problem, but it does raise my eyebrows.) It will not answer all of your questions unless you're a beginner.

Sunset Editorial Staff. Bonsai: Culture and Care of Miniature Trees. Ed. Jack McDowell. Menlo Park, CA. Lane Books, 1974.

Slim, unimposing, and unintimidating, this book is a gentle introduction. The information is general and light, while the photos often help make the text clearer. It will not answer all of your questions unless you're a beginner.

Yunhua, Hu. Penjing: The Chinese Art of Miniature Gardens. Ed. [in Chinese] Zheng Guanghua. Beaverton, Oregon: Timber Press, 1982.

This is another good overview book. The difference is that this one is written with penjing - the Chinese tradition - in mind rather than the Japanese bonsai. This gives it a slightly different perspective. The photos are beautifully clear and the trees shown are inspirational. It also includes many pictures of whole rock-and-tree landscapes, which have their own appeal.