MLA

Luhan, Mabel Dodge, 1879-1962. Johnson, Grace. Box 72, folder 1981. n.d.. https://collections.library.yale.edu/catalog/16789831.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 72, folder 1981"])(n.d.)[Johnson, Grace]. https://collections.library.yale.edu/catalog/16789831.