MLA

Knight, Eric, 1897-1943. Knight, Eric. Box 14, folder 333-35. 1917-42, n.d.. https://collections.library.yale.edu/catalog/2008036.

APA, 6th edition

Knight, Eric, 1897-1943. (["Box 14, folder 333-35"])(1917-42, n.d.)[Knight, Eric]. https://collections.library.yale.edu/catalog/2008036.