Kraft, L. (1976). Gradus: An integrated approach to harmony, counterpoint, and analysis. Norton.
Lua i Stíl Chicago (17ú heag.)Kraft, Leo. Gradus: An Integrated Approach to Harmony, Counterpoint, and Analysis. New York: Norton, 1976.
Lua MLA (9ú heag.)Kraft, Leo. Gradus: An Integrated Approach to Harmony, Counterpoint, and Analysis. Norton, 1976.
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