MLA

Van Vechten, Carl, 1880-1964. "Carlo". Box 253 (Oversize), folder 2830. undated. https://collections.library.yale.edu/catalog/32369806.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 253 (Oversize), folder 2830"])(undated)["Carlo"]. https://collections.library.yale.edu/catalog/32369806.