MLA

Koch, Frederick R. (Frederick Robinson). Music/Quartet, strings, no. 1: incomplete score. Box 212, folder 1554. 1920-22. https://collections.library.yale.edu/catalog/2036820.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 212, folder 1554"])(1920-22)[Music/Quartet, strings, no. 1: incomplete score]. https://collections.library.yale.edu/catalog/2036820.