Sorry! It's really not meant to be a trick. The book is under a CC license. I provide the PDF version at Green Tea Press, the LaTeX source for anyone who wan

Sorry! It's really not meant to be a trick. The book is under a CC license. I provide the PDF version at Green Tea Press, the LaTeX source for anyone who wants to make a modified version, and a not very good HTML version (some of the math is broken). O'Reilly provides the printed and Kindle versions. Right now all versions have the same content, but I will continue to revise, so you can think of the version on Green Tea Press as the draft of the second edition. I know it can be confusing, but I hope the benefits of the free license make up for it.