MLA

Koch, Frederick R. (Frederick Robinson). Music/Troilus and Cressida, act II: score. Box 222, folder 1564. [1947]-54. https://collections.library.yale.edu/catalog/2067779.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 222, folder 1564"])([1947]-54)[Music/Troilus and Cressida, act II: score]. https://collections.library.yale.edu/catalog/2067779.