APA (7th ed.) Citation

Catholic Church, Abbaye Saint-Pierre de Solesmes, & Gajard, J. (1959). Gregorian chant. London.

Chicago Style (17th ed.) Citation

Catholic Church, Abbaye Saint-Pierre de Solesmes, and Joseph Gajard. Gregorian Chant. England: London, 1959.

MLA (8th ed.) Citation

Catholic Church, et al. Gregorian Chant. London, 1959.