MLA

Nicholls, Norton, 1741?-1809. Charles de Bonstetten to Norton Nicholls. Paris. Concerns Thomas Gray; Cambridge University. Box 1, folder 98. 1770 Jun 24. https://collections.library.yale.edu/catalog/17439895.

APA, 6th edition

Nicholls, Norton, 1741?-1809. (["Box 1, folder 98"])(1770 Jun 24)[Charles de Bonstetten to Norton Nicholls. Paris. Concerns Thomas Gray; Cambridge University]. https://collections.library.yale.edu/catalog/17439895.