MLA

Nicholls, Norton, 1741?-1809. Norton Nicholls to Jane Floyer Nicholls. Naples. Concerns Italy. Box 2, folder 160. 1772 Jul 21. https://collections.library.yale.edu/catalog/17439957.

APA, 6th edition

Nicholls, Norton, 1741?-1809. (["Box 2, folder 160"])(1772 Jul 21)[Norton Nicholls to Jane Floyer Nicholls. Naples. Concerns Italy]. https://collections.library.yale.edu/catalog/17439957.