MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 65, folder 1465-1467. 1929 Aug. https://collections.library.yale.edu/catalog/2040065.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 65, folder 1465-1467"])(1929 Aug)[Letters]. https://collections.library.yale.edu/catalog/2040065.