A bit of personal info here... like most pop-up makers, I first started by reverse engineering other pop-up cards and books, not by purchasing a how-to book. Most of the pop-up books I have are children's stories, and most of them have been the damaged display books that all the little kids have opened and closed a thousand times. I would buy these at a discount (yea! because pop-up books are pricey), repair them, and leave the cello wrapped ones for the collectors out there. When looking for a book to buy, I'm not necessarily looking for different pop-up mechanisms, but more for ideas on how to express movement. What's the best way to showing something jumping, flying, stretching?
Back to David A. Carter and james Diaz' book. I threw all my preferences out the window, and purchased a new, cello-wrapped, not-on-sale, sight-unseen book about pop-up mechanisms, and was not disappointed! This is a fairly comprehensive book, complete with clear and concise examples of the geometry behind paper engineering. I was even happy to see that the pages were bound by sewing them in, not gluing them in! Kudos for having the forethought to realize that this reference book will be opened many times.
This book is not for the person who wants step-by-step instructions with print-out patterns, so you're going to have to use your imagination while applying these mechanisms to your own ideas. No pre-conceived notions, I like that!