MLA

Stein, Gertrude, 1874-1946. Buss, Kate. Box 9, folder 104. [1933, 1937, n.d.]. https://collections.library.yale.edu/catalog/2020772.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 9, folder 104"])([1933, 1937, n.d.])[Buss, Kate]. https://collections.library.yale.edu/catalog/2020772.