MLA

Knight, Eric, 1897-1943. Creasser, E. Vernon. Box 14, folder 328-29. n.d.. https://collections.library.yale.edu/catalog/2008031.

APA, 6th edition

Knight, Eric, 1897-1943. (["Box 14, folder 328-29"])(n.d.)[Creasser, E. Vernon]. https://collections.library.yale.edu/catalog/2008031.