MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 75, folder 1582-1585. 1939 Jan-Apr. https://collections.library.yale.edu/catalog/2043458.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 75, folder 1582-1585"])(1939 Jan-Apr)[Letters]. https://collections.library.yale.edu/catalog/2043458.