MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 72, folder 1547-1554. 1935 Feb-Aug. https://collections.library.yale.edu/catalog/2041876.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 72, folder 1547-1554"])(1935 Feb-Aug)[Letters]. https://collections.library.yale.edu/catalog/2041876.