MLA

Townshend, George Townshend, Marquis, 1724-1807. Courtney, John. Box 9. 1770 January 10. https://collections.library.yale.edu/catalog/16684974.

APA, 6th edition

Townshend, George Townshend, Marquis, 1724-1807. (["Box 9"])(1770 January 10)[Courtney, John]. https://collections.library.yale.edu/catalog/16684974.