I'm not sure if people read books on the Alexander Technique anymore. The truth is that even if they're outdated, there's a tremendous opportunity for students to get ahead by learning from these books. If you're serious about developing a practice, then I recommend you start with the introductory books.
Also, books on the Alexander Technique have the most impact after you've studied for a little while, and are almost always confusing if you're brand new to the technique. If you haven't taken a lesson, then don't both reading a book...go for at least one lesson; it's best communicated experientially (like music). Student's tell me reading helps with making sense of their experiences. That was (and continues to be) the case for me too. - Mark
The Alexander Technique: A Skill for Life By Pedro de Alcantara
Body Learning: An introduction to the Alexander Technique By Michael J. Gelb (*The science/explanations are dated but still a good into read for students).
The Use of the Self By F.M. Alexander
Getting Nerdy Books:
Freedom to Change: Development and Science of the Alexander Technique By Frank Pierce Jones
Even More Nerdy:
All other books by F.M Alexander
Thinking Fast and Slow By Daniel Kahneman
Chair: Rethinking Body Culture And Design By Galen Cranz
Awareness Through Movement By Moshe Feldenkrais
Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World By Christopher McDougall