MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 85, folder 1713-1722. 1929 Apr-Aug. https://collections.library.yale.edu/catalog/2039974.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 85, folder 1713-1722"])(1929 Apr-Aug)[Letters]. https://collections.library.yale.edu/catalog/2039974.