MLA

McKay, Claude, 1890-1948. Cunard, Nancy. Box 2, folder 54-57. 1932-33, n.d.. https://collections.library.yale.edu/catalog/16742349.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 2, folder 54-57"])(1932-33, n.d.)[Cunard, Nancy]. https://collections.library.yale.edu/catalog/16742349.