The Guerrilla CG Project website is down by restricted access but some of the video lives on Vimeo. In honor of Pi Day, below are a couple of videos on rotation by Andrew Silke, The Rotation Problem and Euler Rotations Explained:
Euler Rotations, the most common method for orienting objects in 3d. It's by-product "gimbal lock" can cause headaches for animators because the animated motion can move in strange ways. Here we learn how euler's "rotation order" is a bit like hierachies, and how changing this order can help us to avoid gimbal problems. This is demonstrated with a solution to a common camera problem, by finding the correct rotation order.
Chris and Trish Meyer explain this (Euler XYZ vs. the quaternion Orientation) and related issues for After Effects in Creating Motion Graphics. There's more of course in AE Help. Here's Andrew Silke:
The Rotation Problem from The Guerrilla CG Project on Vimeo.