MLA

Wilson, Edmund, 1895-1972. Mallet. Box 204, folder 5013. n.d.. https://collections.library.yale.edu/catalog/2005096.

APA, 6th edition

Wilson, Edmund, 1895-1972. (["Box 204, folder 5013"])(n.d.)[Mallet]. https://collections.library.yale.edu/catalog/2005096.