daryl's encyclopedia of sleights vol. 2 or 3 are cool, not quite sure which one teaches about the crimp, i think using it is one of the great ways to just cut straight to the card you want to be controlled even after a spectator shuffled the deck (pretty neat eh?). Plus learning the up the ladder cut and the controlled strip shuffle is also great for tablework. Oh and btw, the up the ladder cut could be used to control a single or multiple cards from the top the the bottom and vice versa aside from being an eye candy.