MLA

Stieglitz, Alfred, 1864-1946. Barringer, Anna. Box 180, folder 2994. 1918 Nov. https://collections.library.yale.edu/catalog/17105679.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 180, folder 2994"])(1918 Nov)[Barringer, Anna]. https://collections.library.yale.edu/catalog/17105679.