MLA

Koch, Frederick R. (Frederick Robinson). Music/Unidentified/Dance music: second flageolet part. Box 330, folder 1853. n.d.. https://collections.library.yale.edu/catalog/12218977.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 330, folder 1853"])(n.d.)[Music/Unidentified/Dance music: second flageolet part]. https://collections.library.yale.edu/catalog/12218977.