MLA

Luhan, Mabel Dodge, 1879-1962. Stein, Gertrude. Box 32, folder 927-930. 1911-22, n.d.. https://collections.library.yale.edu/catalog/2055094.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 32, folder 927-930"])(1911-22, n.d.)[Stein, Gertrude]. https://collections.library.yale.edu/catalog/2055094.