MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 90, folder 1779-1781. 1935 Oct-Nov. https://collections.library.yale.edu/catalog/2042391.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 90, folder 1779-1781"])(1935 Oct-Nov)[Letters]. https://collections.library.yale.edu/catalog/2042391.