Apel, W. (1947). Masters of the keyboard: A brief survey of pianoforte music. Harvard Univ. Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रApel, Willi. Masters of the Keyboard: A Brief Survey of Pianoforte Music. Cambridge: Harvard Univ. Press, 1947.
एमएलए (9वां संस्करण) प्रशस्ति पत्रApel, Willi. Masters of the Keyboard: A Brief Survey of Pianoforte Music. Harvard Univ. Press, 1947.
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