MLA

Koch, Frederick R. (Frederick Robinson). Music/Unidentified/Dance music for orchestra. Box 179, folder 1521. n.d.. https://collections.library.yale.edu/catalog/12239814.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 179, folder 1521"])(n.d.)[Music/Unidentified/Dance music for orchestra]. https://collections.library.yale.edu/catalog/12239814.