MLA

Stieglitz, Alfred, 1864-1946. Eickemeyer, Rudolf. Box 16, folder 375. 1894 Dec. https://collections.library.yale.edu/catalog/17105624.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 16, folder 375"])(1894 Dec)[Eickemeyer, Rudolf]. https://collections.library.yale.edu/catalog/17105624.