The autor of „The Podmedics Do Surgery“, Dr. Wallitt, stated in an interview (highlighting by me):
From a technical perspective it was incredibly easy to create. In the past, to create a similar textbook would have required a detailed knowledge of Xcode, Objective-C and Cocoa touch. However with iBooks author, Apple have created a gateway for anyone with any word processing ability to create compelling and high-quality content.
It’s bold to prognose that in 12 months time there will be a lot of medical textbooks in the Apple store, some for free, some for little money? And even some German ones? Stay tuned!