MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 93, folder 1836-1837. 1942 Nov. https://collections.library.yale.edu/catalog/2044033.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 93, folder 1836-1837"])(1942 Nov)[Letters]. https://collections.library.yale.edu/catalog/2044033.