MLA

Stieglitz, Alfred, 1864-1946. Frank Eugene. Box 130, folder 2527. ca. 1907. https://collections.library.yale.edu/catalog/2002566.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 130, folder 2527"])(ca. 1907)[Frank Eugene]. https://collections.library.yale.edu/catalog/2002566.