MLA

Koch, Frederick R. (Frederick Robinson). Music/Fest-Ouverture. Box 334, folder 1919. n.d.. https://collections.library.yale.edu/catalog/10171192.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 334, folder 1919"])(n.d.)[Music/Fest-Ouverture]. https://collections.library.yale.edu/catalog/10171192.