MLA

Koch, Frederick R. (Frederick Robinson). Music/Troilus and Cressida, act I: score. Box 221, folder 1563. [1947]-54. https://collections.library.yale.edu/catalog/2067766.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 221, folder 1563"])([1947]-54)[Music/Troilus and Cressida, act I: score]. https://collections.library.yale.edu/catalog/2067766.