Izvornik: Alfred's MusicTech Series, Book 1. Sharps, Flats, and Naturals. Playing Keyboard. Tom Rudolph. Organ sheet music. Piano sheet music.
Prijevod: Alfredov MusicTech serija, knjiga 1. Igranje tipkovnice. Orgulje note. Piano note. Alfredov MusicTech serija, knjiga 1. Igranje tipkovnice.