MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 228, folder 4040-4051. 1975-77. https://collections.library.yale.edu/catalog/10576937.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 228, folder 4040-4051"])(1975-77)[Letters]. https://collections.library.yale.edu/catalog/10576937.