MLA

Koch, Frederick R. (Frederick Robinson). Music/Christopher Columbus. Box 199, folder 1541. [1942]. https://collections.library.yale.edu/catalog/2067828.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 199, folder 1541"])([1942])[Music/Christopher Columbus]. https://collections.library.yale.edu/catalog/2067828.