My father was a professor and a pilot. On a birthday, we bought him a blank book with the cover imprinted “All I know about Aviation”.with his name as author. He then placed the books in the library restricted section and assigned the book as required reading. Each student could only check out books in this section for 24 hours, so usually set aside an entire day to read the book. Not one of the students let on to anyone else that the book was empty, and all of them had checked out the book!