MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 89, folder 1772-1778. 1935 May-Sep. https://collections.library.yale.edu/catalog/2041995.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 89, folder 1772-1778"])(1935 May-Sep)[Letters]. https://collections.library.yale.edu/catalog/2041995.