MLA

Nicholls, Norton, 1741?-1809. George Nicholls to Jane Floyer Nicholls. Ditchley Park. Concerns Norton Nicholls. Box 1, folder 122. 1771 Sep 30. https://collections.library.yale.edu/catalog/17439919.

APA, 6th edition

Nicholls, Norton, 1741?-1809. (["Box 1, folder 122"])(1771 Sep 30)[George Nicholls to Jane Floyer Nicholls. Ditchley Park. Concerns Norton Nicholls]. https://collections.library.yale.edu/catalog/17439919.