MLA

Stieglitz, Alfred, 1864-1946. McAlpin, David Hunter and Sally. Box 200, folder 3457-3459. 1940-85, n.d.. https://collections.library.yale.edu/catalog/9998591.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 200, folder 3457-3459"])(1940-85, n.d.)[McAlpin, David Hunter and Sally]. https://collections.library.yale.edu/catalog/9998591.