APA (7th ed.) Citation

Mozart, W. A., Richter, K., Moser, E., Haefliger, E., & Engen, K. (1975). Requiem K.V. 626. [Karl Richter?].

Chicago Style (17th ed.) Citation

Mozart, Wolfgang Amadeus, Karl Richter, Edda Moser, Ernst Haefliger, and Kieth Engen. Requiem K.V. 626. [München?]: [Karl Richter?], 1975.

MLA (9th ed.) Citation

Mozart, Wolfgang Amadeus, et al. Requiem K.V. 626. [Karl Richter?], 1975.