MLA

Stieglitz, Alfred, 1864-1946. McCausland, Elizabeth. Box 201, folder 3461. 1932. https://collections.library.yale.edu/catalog/17105686.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 201, folder 3461"])(1932)[McCausland, Elizabeth]. https://collections.library.yale.edu/catalog/17105686.