It is the Graphic Artists Guild Handbook, Pricing and Ethical Guidelines ($35); almost every page on it has something useful for you from a thourough explanation of Copyrights, how to register your work and how to take advantage of them by Licensing your work or how to potect yourself against Copyright Infringement. Pricing Guidelines to pretty much anything related to Graphic Design such as Corporate Logos, Advertising rates, Publishing rates, Packaging, Writing your own Contracts, etc.
      To me this is my new Bible, I've been using it for only a couple of months but it's been the best investment I've ever made and I highly recommend it. I can almost assure you it'll be the best 35 bucks you'll ever spend.
Sincerely,
Victor Sepulveda
www.VictorSepulveda.com