MLA

Koch, Frederick R. (Frederick Robinson). Music/Missa brevis. Box 339, folder 1982. 1966. https://collections.library.yale.edu/catalog/2112290.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 339, folder 1982"])(1966)[Music/Missa brevis]. https://collections.library.yale.edu/catalog/2112290.