Drawn to Life is a two volume collection of the legendary lectures from long-time Disney animator Walt Stanchfield. For over twenty years, Walt helped breathe life into the new golden age of animation with these teachings at the Walt Disney Animation Studios.
Frame by Frame is a blog that displays sequential images from various animated films for study and appreciation. It also shows the gif to supply reference for timing.
Living Lines Library is an amazing resource full of pencil tests, drawings, documentaries and more from the animation legends!
The Animation Podcast was a podcast by Clay Kaytis that focused on interviews from animation veterans (mainly Disney). It is no longer being updated but still has a bunch of podcasts to listen to.
The Illusion of Life by two of Disney’s ‘Nine Old Men’, Frank Thomas and Ollie Johnston is another must-have book. It is basically a bible of animation and explains everything about the history of animation, where the principles and techniques came from and more!
Animator's Resource Kit 