Long before the advent of iTunes LP, Apple offered—and still does offer—so-called Digital Booklets with certain album purchases. Unfortunately, these files have been basically useless outside of iTunes, as Apple has never offered a good way to organize and view them on its portable devices—until it added PDF support iBooks. While it might not do it automatically, iTunes does offer an easy way to gather these Booklets up and move them over to iBooks.
The first step is to create a Smart Playlist based on the criteria that the Kind attribute contains the word PDF, as shown in the image above. Once that’s done and you’ve verified there isn’t anything in the playlist that shouldn’t be there, simply select all of the Booklets and go to File > Get Info, or else use the keyboard shortcut command-I. In the window that appears, click on Options, and then go to Media Kind and select “Book.” iTunes will then go through and relabel all the Booklets as Books instead of Music files, moving them into the Books section automatically. If you’ve got Automatic Downloads setup, the Booklets should automatically start appearing in the Libraries of your iOS devices; if not, they’ll transfer over the next time you sync, at long last giving you a chance to see the liner notes from some questionable album purchase you made in 2005.