MLA

Stein, Gertrude, 1874-1946. Yale University Library. Box 131, folder 2879. 1938-46. https://collections.library.yale.edu/catalog/17105777.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 131, folder 2879"])(1938-46)[Yale University Library]. https://collections.library.yale.edu/catalog/17105777.