MLA

Stein, Gertrude, 1874-1946. About Gertrude Stein. Box 142, folder 3340-3341. 1926-27. https://collections.library.yale.edu/catalog/2065753.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 142, folder 3340-3341"])(1926-27)[About Gertrude Stein]. https://collections.library.yale.edu/catalog/2065753.