MLA

Knopf, Blanche W., 1894-196, Van Vechten, Carl, 1880-1964. Boucher, Margot. Box 337 | Folder 4269. 1954 September 4. https://collections.library.yale.edu/catalog/2031092.

APA, 6th edition

Knopf, Blanche W., 1894-196, & Van Vechten, Carl, 1880-1964. (["Box 337 | Folder 4269"])(1954 September 4)[Boucher, Margot]. https://collections.library.yale.edu/catalog/2031092.