MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 84, folder 1706. 1928 Jan. https://collections.library.yale.edu/catalog/2039729.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 84, folder 1706"])(1928 Jan)[Letters]. https://collections.library.yale.edu/catalog/2039729.