MLA

Stein, Gertrude, 1874-1946. About Gertrude Stein. Box 142, folder 3336-3339. 1922-25. https://collections.library.yale.edu/catalog/2065752.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 142, folder 3336-3339"])(1922-25)[About Gertrude Stein]. https://collections.library.yale.edu/catalog/2065752.