MLA

Van Vechten, Carl, 1880-1964. Bishop, Christopher, and Robert Grosvenor Bishop. Box 336 | Folder 4246. 1949 June 18. https://collections.library.yale.edu/catalog/2030851.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 336 | Folder 4246"])(1949 June 18)[Bishop, Christopher, and Robert Grosvenor Bishop]. https://collections.library.yale.edu/catalog/2030851.