MLA

Koch, Frederick R. (Frederick Robinson). Music/Jeune fillette reste coquette. Box 329, folder 1835. n.d.. https://collections.library.yale.edu/catalog/12218305.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 329, folder 1835"])(n.d.)[Music/Jeune fillette reste coquette]. https://collections.library.yale.edu/catalog/12218305.