MLA

Wilson, Edmund, 1895-1972. Policeman. Box 204, folder 5003. n.d.. https://collections.library.yale.edu/catalog/2005083.

APA, 6th edition

Wilson, Edmund, 1895-1972. (["Box 204, folder 5003"])(n.d.)[Policeman]. https://collections.library.yale.edu/catalog/2005083.