MLA

Luhan, Mabel Dodge, 1879-1962. Goldman, Emma. Box 15, folder 422. 1913-14, n.d.. https://collections.library.yale.edu/catalog/17085354.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 15, folder 422"])(1913-14, n.d.)[Goldman, Emma]. https://collections.library.yale.edu/catalog/17085354.