Below is the book Arturo Sandoval mentions to Tom Hooten. The 30 Velocity Studies book by Claude Gordon was derived from the Hannon Piano Studies, which are two handed scale patterns. Claude started it on Pedal C and there are almost 20 different articulations to apply to each scale study that are listed at the start of the book. It’s reasonable to spend a month and no less than two weeks on each study. This book was intended to be the next phase of range studies after completing the Systematic Approach book.