Studien zum Klavierspiel Beethovens und seiner Zeitgenossen, by Herbert Grundmann and Paul Mies
October 1, 1971- PDF https://www.jstor.org/stable/40373289
Five Centuries of Keyboard Music, by John Gillespie
October 1, 1967- PDF https://www.jstor.org/stable/40373204
Piano Teacher's Professional Handbook, by Gordon Terwilliger
October 1, 1967- PDF https://www.jstor.org/stable/40373205
The Basic Piano Program at Harvard University
October 1, 1964- PDF https://www.jstor.org/stable/40373135