“The relation of tonic to dominant is the foundation of Western triadic tonality. The attempt of the early nineteenth century to substitute third or mediant relationships for the classical dominant amounted to a frontal attack on the principles of tonality, and it eventually contributed to the ruin of triadic tonality. This ruin was accomplished from within the system, however, as mediant relationships were essential to tonality as conceived in the eighteenth century.”

"The Folk Songs of Hungary" in Pro Musica VII (October 1928)
Context: Our peasant music, naturally, is invariably tonal, if not always in the sense that the inflexible major and minor system is tonal. (An "atonal" folk-music, in my opinion, is unthinkable.) Since we depend upon a tonal basis of this kind in our creative work, it is quite self-evident that our works are quite pronouncedly tonal in type. I must admit, however, that there was a time when I thought I was approaching a species of twelve-tone music. Yet even in works of that period the absolute tonal foundation is unmistakable.

Quoted in Reich, Willi (1971). Schoenberg: A Critical Biography, p. 34. Translated by Leo Black.

Feeling and Form, ch. 1, p. 27, Scribner (1953)

Prokofiev’s piano sonatas : a guide for the listener and the performer (2008), Prokofiev: His Life and the Evolution of His Musical Language

Joseph Fétis, (1844). Traité complet de la théorie et de la pratique de l'harmonie contenant la doctrine de la science et de l'art, 2d ed., p. 166. Brussels and Paris.

As quoted by David Milner, "Akira Ifukube Interview I" http://www.davmil.org/www.kaijuconversations.com/ifukub.htm, Kaiju Conversations (December 1992)

As quoted by J. E. Müller, Le Fauvisme, Paris, Hazan, 1956, p. 92

Part I. Introduction. 1. The Musical Language of the Late Eighteenth Century
Classical Style: Haydn, Mozart, Beethoven (Expanded edition, 1997)

'Terms' p. 74
Search for the Real and Other Essays (1948)