MLA

Van Vechten, Carl, 1880-1964. Zlotchever, Eve. Box 175, folder 2255. 1918 February 21. https://collections.library.yale.edu/catalog/17064306.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 175, folder 2255"])(1918 February 21)[Zlotchever, Eve]. https://collections.library.yale.edu/catalog/17064306.