MLA

Stein, Gertrude, 1874-1946. Wilder, Thornton. Box 131, folder 2857-2859. 1935-45. https://collections.library.yale.edu/catalog/9998408.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 131, folder 2857-2859"])(1935-45)[Wilder, Thornton]. https://collections.library.yale.edu/catalog/9998408.