^Haluska (2003), p.xxiv. Pythagorean minor seventh.
^Haluska, Jan (2003). The Mathematical Theory of Tone Systems, p.xxiii. ISBN0-8247-4714-3. Just minor seventh.
^Benward & Saker (2003). Music: In Theory and Practice, Vol. I, p.53. Seventh Edition. ISBN978-0-07-294262-0.
^"On Certain Novel Aspects of Harmony", p.119. Eustace J. Breakspeare. Proceedings of the Musical Association, 13th Sess., (1886 - 1887), pp. 113-131. Published by: Oxford University Press on behalf of the Royal Musical Association.
^"The Heritage of Greece in Music", p.89. Wilfrid Perrett. Proceedings of the Musical Association, 58th Sess., (1931 - 1932), pp. 85-103. Published by: Oxford University Press on behalf of the Royal Musical Association.