MLA

Koch, Frederick R. (Frederick Robinson). Music/Letzte Lieder. Box 335, folder 1929. 1948 Aug 14. https://collections.library.yale.edu/catalog/15949722.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 335, folder 1929"])(1948 Aug 14)[Music/Letzte Lieder]. https://collections.library.yale.edu/catalog/15949722.