MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 74, folder 1569-1575. 1937 Jun-Oct. https://collections.library.yale.edu/catalog/2042636.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 74, folder 1569-1575"])(1937 Jun-Oct)[Letters]. https://collections.library.yale.edu/catalog/2042636.