MLA

Luhan, Mabel Dodge, 1879-1962. Wells, Cady. Box 66, folder 1804. n.d.. https://collections.library.yale.edu/catalog/10268292.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 66, folder 1804"])(n.d.)[Wells, Cady]. https://collections.library.yale.edu/catalog/10268292.