MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 73, folder 1560-1566. 1936 May-Sep. https://collections.library.yale.edu/catalog/2042269.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 73, folder 1560-1566"])(1936 May-Sep)[Letters]. https://collections.library.yale.edu/catalog/2042269.