The book first went out as a "stand alone" text; however, it was later changed to work in conjunction with this website. You will need to know what version you have in order to access this website.

Newer version- The back cover of the book mentions this website in the last paragraph.

Older version- The back cover of the book does not mention www.speclass.com in the last paragraph. This version also contains some typos that are not in the current version (yep, a collector's item).