Guitar textbooks. I think there are some rare ones. I used them for guitar practice, but they were also useful when creating guitar tracks for DTM (desktop music). ① Sugu Tsukaeru! Pentatonic Scale Phrase Collection [DVD] (Not a book. It's a DVD. See photo 3) ② Guitar Chord Voicing Complete Guide! ③ Guitar Magazine Guitar Scale Encyclopedia 396 ④ BOX Style Lead Guitar Freedom: Achieve ad-libs for each chord progression just by learning 3 BOXes ⑤ Imasugu Tsukaeru Chou Hiden Phrase 80!! (Super Secret Phrases You Can Use Now!) ⑥ Eleki Guitar de Gakkyoku ni Mahou wo Kakeru (Casting Magic on Songs with Electric Guitar) (No CD. See photo 11) I'm also listing many other books I accumulated when I was into DTM, so please take a look.