MLA

Koch, Frederick R. (Frederick Robinson). Music/Troilus and Cressida: draft fragment and revisions. Box 306, folder 1648. 1976, n.d.. https://collections.library.yale.edu/catalog/2067781.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 306, folder 1648"])(1976, n.d.)[Music/Troilus and Cressida: draft fragment and revisions]. https://collections.library.yale.edu/catalog/2067781.