MLA

Stieglitz, Alfred, 1864-1946. Russell, Morgan. Box 43, folder 1017. 1916-21. https://collections.library.yale.edu/catalog/2046731.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 43, folder 1017"])(1916-21)[Russell, Morgan]. https://collections.library.yale.edu/catalog/2046731.