APA (7th ed.) Citation

Bryden, J. R., & Hughes, D. G. An index of Gregorian chant. Harvard Univ. Press.

Chicago Style (17th ed.) Citation

Bryden, John R., and David G. Hughes. An Index of Gregorian Chant. Cambridge, Mass: Harvard Univ. Press.

MLA (8th ed.) Citation

Bryden, John R., and David G. Hughes. An Index of Gregorian Chant. Harvard Univ. Press.