MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 94, folder 1850-1855. 1945 Jun-Aug. https://collections.library.yale.edu/catalog/2044267.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 94, folder 1850-1855"])(1945 Jun-Aug)[Letters]. https://collections.library.yale.edu/catalog/2044267.