title_body: backing up books from iBooks
upvoted_answer: If you sync your phone to your computer, you should be able to see all your files in this location:
  ~/Library/Containers/com.apple.BKAgentService/Data/Documents/iBooks/Books
  Use a terminal to go there, or press CMD+Shift+G in Finder and paste in the path.
  
  Note that your books will not be named as titles but rather the hash of the file. With some basic plist hacking and bash scripting you can rename them so something useful, or just throw them into Calibre and let it do it's thing.