MLA

Koch, Frederick R. (Frederick Robinson). Music/Hamlet. Box 207, folder 1549. [1947]. https://collections.library.yale.edu/catalog/2035671.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 207, folder 1549"])([1947])[Music/Hamlet]. https://collections.library.yale.edu/catalog/2035671.