Harm van Veen, The Tao of Kite-Flying, 55 pages, ISBN 0-937315-01-X

A slim but information-packed booklet. It presents a theoretical analysis of the fundamental problems of flying and building single line kites: How to achieve stability (construction, bridle, weight); considerations for upscaling and downscaling.
This is a thought-provoking book and fascinating reading for any kite builder. It gives you a mental framework for analysing your own constructions and considering possible improvements. I recommend this book, but I must add that it didn't help me quite as much as I was hoping: Van Veen's kite model is naturally greatly simplified and I have trouble applying his principles to many of my kites.