Harder, P. O. (1990). Harmonic materials in tonal music: A programmed course (6th ed.). Allyn and Bacon.
Lua i Stíl Chicago (17ú heag.)Harder, Paul O. Harmonic Materials in Tonal Music: A Programmed Course. 6th ed. Boston: Allyn and Bacon, 1990.
Lua MLA (9ú heag.)Harder, Paul O. Harmonic Materials in Tonal Music: A Programmed Course. 6th ed. Allyn and Bacon, 1990.
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