MLA

Luhan, Mabel Dodge, 1879-1962. O'Keeffe, Georgia. Box 27, folder 778-782. 1925-52, n.d.. https://collections.library.yale.edu/catalog/17085362.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 27, folder 778-782"])(1925-52, n.d.)[O'Keeffe, Georgia]. https://collections.library.yale.edu/catalog/17085362.