MLA

McKay, Claude, 1890-1948. United States. Box 16, folder 499. n.d.. https://collections.library.yale.edu/catalog/16742375.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 16, folder 499"])(n.d.)[United States]. https://collections.library.yale.edu/catalog/16742375.