MLA

Nicholls, Norton, 1741?-1809. Arthur Cooke to Norton Nicholls. n.p. Concerns family. Box 8, folder 823. 1808 Oct 7. https://collections.library.yale.edu/catalog/10051464.

APA, 6th edition

Nicholls, Norton, 1741?-1809. (["Box 8, folder 823"])(1808 Oct 7)[Arthur Cooke to Norton Nicholls. n.p. Concerns family]. https://collections.library.yale.edu/catalog/10051464.