MLA

Balguy, John, 1686-1748. [Autograph letter signed] 1743 November 10 [to] Thomas Balguy, St. Johns College, Cambridge. Folder 6. 1743 November 10. https://collections.library.yale.edu/catalog/10000030.

APA, 6th edition

Balguy, John, 1686-1748. (["Folder 6"])(1743 November 10)[[Autograph letter signed] 1743 November 10 [to] Thomas Balguy, St. Johns College, Cambridge]. https://collections.library.yale.edu/catalog/10000030.