MLA

Stein, Gertrude, 1874-1946. Carpenter, Edna. Box 100, folder 1941. 1945 Sep 27. https://collections.library.yale.edu/catalog/17105726.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 100, folder 1941"])(1945 Sep 27)[Carpenter, Edna]. https://collections.library.yale.edu/catalog/17105726.