MLA

Luhan, Mabel Dodge, 1879-1962. Kuttner, Alfred. Box 22, folder 617. 1914-16, n.d.. https://collections.library.yale.edu/catalog/17085356.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 22, folder 617"])(1914-16, n.d.)[Kuttner, Alfred]. https://collections.library.yale.edu/catalog/17085356.