MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 70, folder 1526-1531. 1934 Jan-Apr. https://collections.library.yale.edu/catalog/2041347.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 70, folder 1526-1531"])(1934 Jan-Apr)[Letters]. https://collections.library.yale.edu/catalog/2041347.