Also, the book licence is very permissive.

    "This book is Copyright (C) 2010 by Zed A. Shaw. You are free to distribute this book to anyone you want, so long as you do not charge anything for it, and it is not altered. You must give away the book in its entirety, or not at all."

As such, if you can't afford to buy yourself a copy with the above coupon code, send me an email at (gregorylyons@gmail.com) and I will send you a copy.