MLA

Koch, Frederick R. (Frederick Robinson). Music/Tosca. Box 288, folder 1630. n.d.. https://collections.library.yale.edu/catalog/2037348.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 288, folder 1630"])(n.d.)[Music/Tosca]. https://collections.library.yale.edu/catalog/2037348.