MLA

Koch, Frederick R. (Frederick Robinson). Music/Rosemonde. Box 331, folder 1873. 1954 May. https://collections.library.yale.edu/catalog/10598053.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 331, folder 1873"])(1954 May)[Music/Rosemonde]. https://collections.library.yale.edu/catalog/10598053.