MLA

Koch, Frederick R. (Frederick Robinson). Music/Zazà. Box 122, folder 1464. n.d.. https://collections.library.yale.edu/catalog/2006286.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 122, folder 1464"])(n.d.)[Music/Zazà]. https://collections.library.yale.edu/catalog/2006286.