If you can't find it listed either in the book itself or in Apple's bookstore, then it's quite likely that the publisher of the book did not include an author's name.
By the way, the "Using the Community" forum (where you first posted, if this thread gets moved) is for questions about the communities themselves. You'll be more likely to get useful advice if you post in the forum specifically for your device or operating system. As you work to become familiar with the Community, you may wish to bookmark this forum site map:
Site Map - Apple Community
Regards.