In January 2013, Disney Animation Studios released a box-set of nine flip books that pay tribute to the "Nine Old Men" of Disney animation — artists who pioneered the animation techniques that define the field even today. I only just found out about these today — they're amazing. Each book shows the animation as line-art, really capturing the character and movement the animators imbued their creations with. This video does a good job of showing off the books. The box also includes a short explanatory book, but this isn't really about reading material — the value is all in having the cel-by-cel line art to marvel upon.
Walt Disney Animation Studios The Archive Series Walt Disney's Nine Old Men: The Flipbooks
