MLA

Vilmorin, Louise de, 1902-1969. Letters to Duff Cooper. Box 1 | Folder 3. 1943-53, n.d.. https://collections.library.yale.edu/catalog/16691719.

APA, 6th edition

Vilmorin, Louise de, 1902-1969. (["Box 1 | Folder 3"])(1943-53, n.d.)[Letters to Duff Cooper]. https://collections.library.yale.edu/catalog/16691719.