MLA

Luhan, Mabel Dodge, 1879-1962. Witter Bynner sketch. Box 66, folder 1809. n.d.. https://collections.library.yale.edu/catalog/10268294.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 66, folder 1809"])(n.d.)[Witter Bynner sketch]. https://collections.library.yale.edu/catalog/10268294.