MLA

Stein, Gertrude, 1874-1946. Levy, Harriet. Box 114, folder 2369-2370. 1908-35, n.d.. https://collections.library.yale.edu/catalog/2066858.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 114, folder 2369-2370"])(1908-35, n.d.)[Levy, Harriet]. https://collections.library.yale.edu/catalog/2066858.