MLA

Koch, Frederick R. (Frederick Robinson). Music/Vom Berge. Box 345, folder 2047. n.d.. https://collections.library.yale.edu/catalog/2043678.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 345, folder 2047"])(n.d.)[Music/Vom Berge]. https://collections.library.yale.edu/catalog/2043678.