[1] Michael Praetorius, Theatrum Instrumentorum, Wolfenbüttel, 1620, pl. 14.

[2] Ibid., pl. 6.

[3] Querinus van Blankenburg, Elementa Musica, The Hague, 1739.

[4] Translation by Arthur Mendel in "Devices for Transposition in the Organ before 1600," Acta Musicologica, 1949, p. 33.

[5] Sibyl Marcuse, "Transposing Keyboards on Extant Flemish Harpsichords," Musical Quarterly, July 1952.

[6] Michael Praetorius, Syntagma Musicum, Wolfenbüttel, 1614–1620, vol. 2 (Organographia), chapter 2.

[7] Translation by Arthur Mendel in "Pitch in the 16th and early 17th Centuries, Part II," Musical Quarterly, April 1948.

[8] Marin Mersenne, Harmonie Universelle, Paris, 1636, p. 101.