On Amazon's recommendation, I just got a new book I haven't seen mentioned here before: Jorgensen, Elaina M. Field Guide to Squids and Octopods of the Eastern North Pacific and Bering Sea 2009 ISBN 978-1-56612-139-2 This is a great reference to the local cephs off the U.S. and Canadian Northern West Coast. Lots of color pictures, and good illustrations. It has an extensive glossary, and of course an identification key, and index of common and scientific names. It doesn't cover Southern California, so it's missing our friends the bimacs, but it appears to be almost complete for the cephalopod fauna of the Pacific Northwest... the only omission I've noticed is Architeuthis. At $25, I highly recommend it.