All the music is in the public domain. Scores from the music21 corpus; Moonlight Sonata, Rondo alla Turca, The Entertainer and the Chopin preludes encoded by Craig Stuart Sapp (CC BY-NC-SA 4.0); Für Elise from the Mutopia Project; the Chinese melodies as given on Wikipedia; Bèo dạt mây trôi and Cò lả transcribed from Dương Huyền Ly's lead sheets on truongca.com, without the grace notes; the Clementi and Schumann from the OpenSheetMusicDisplay samples. The chorale, the Foster song, the Vietnamese and Chinese songs and the beginner tunes are arranged here for two hands.