MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Gladys Seymour, Marcel Duchamp, Charles Seymour, KSD, Charles H. Sawyer (4 prints). Box 70, folder 1804. [1950 Apr 30]. https://collections.library.yale.edu/catalog/2040531.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 70, folder 1804"])([1950 Apr 30])[Gladys Seymour, Marcel Duchamp, Charles Seymour, KSD, Charles H. Sawyer (4 prints)]. https://collections.library.yale.edu/catalog/2040531.