MLA

Nicholls, Norton, 1741?-1809. George Nicholls to Jane Floyer Nicholls. Ditchleys. Concerns Norton Nicholls. Box 1, folder 131. 1771 Dec 15. https://collections.library.yale.edu/catalog/17439928.

APA, 6th edition

Nicholls, Norton, 1741?-1809. (["Box 1, folder 131"])(1771 Dec 15)[George Nicholls to Jane Floyer Nicholls. Ditchleys. Concerns Norton Nicholls]. https://collections.library.yale.edu/catalog/17439928.