MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 230, folder 4067-4077. 1983. https://collections.library.yale.edu/catalog/10577012.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 230, folder 4067-4077"])(1983)[Letters]. https://collections.library.yale.edu/catalog/10577012.