Apel, W. 1., & Apel, W. 1. (1973). Gregorian chant. London, Sydney: Indiana University Press.
Chicago Style CitationApel, Willi 1893-1988, and Willi 1893-1988 Apel. Gregorian Chant. London, Sydney: Indiana University Press, 1973.
MLA CitationApel, Willi 1893-1988, and Willi 1893-1988 Apel. Gregorian Chant. London, Sydney: Indiana University Press, 1973.
Warning: These citations may not always be 100% accurate.