The three books are:
II. The Golden Apple
The high status of the book in the hacker community can be traced back to Karl Koch (1965-1989), an infamous German hacker and allegedly a KGB agent, who went by the handle of 'Captain Hagbard Celine' - one of the main characters of the book. Koch was fascinated by the book, which was given to him by his father in 1979. Koch's suicide in 1989, which resulted from psychological illness due to a long history of drug abuse, made him into another cult figure of the German hacker underground.