MLA

Stein, Gertrude, 1874-1946. Olivier, Fernande Belvallé. Box 153, folder 3782-3787. ca. 1906-1909. https://collections.library.yale.edu/catalog/9998184.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 153, folder 3782-3787"])(ca. 1906-1909)[Olivier, Fernande Belvallé]. https://collections.library.yale.edu/catalog/9998184.