MLA

Butts, Mary, 1890-1937. Wilkinson, Louis. Box 2, folder 45. 1932 Aug 27. https://collections.library.yale.edu/catalog/16947644.

APA, 6th edition

Butts, Mary, 1890-1937. (["Box 2, folder 45"])(1932 Aug 27)[Wilkinson, Louis]. https://collections.library.yale.edu/catalog/16947644.