Let's forget Loomis and Bridgman for a moment. What are some of your favorite lesser known artbooks?

For me, I recently found out that Marco Bucci has a book. The book is titled "Creativity and the Campfire" and covers his journey learning art. I bought it yesterday and finished it today; I can't recommend it enough, even though it's on the self-help side.
Also, "The Quick Pose" by Erin Meads features a nice collection of amazing quicksketches.