MLA

Stein, Gertrude, 1874-1946. Olivier, Fernande Belvallé. Box 117, folder 2522-2523. 1907-33, n.d.. https://collections.library.yale.edu/catalog/32248151.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 117, folder 2522-2523"])(1907-33, n.d.)[Olivier, Fernande Belvallé]. https://collections.library.yale.edu/catalog/32248151.