MLA

Amherst of Arracan, William Pitt Amherst, Earl, 1773-1857. Earl Amherst of Arracan letters to Sarah, Countess of Arracan, 1806-1822.. Box 1 | Folder 15. 1821-24. https://collections.library.yale.edu/catalog/11695521.

APA, 6th edition

Amherst of Arracan, William Pitt Amherst, Earl, 1773-1857. (["Box 1 | Folder 15"])(1821-24)[Earl Amherst of Arracan letters to Sarah, Countess of Arracan, 1806-1822.]. https://collections.library.yale.edu/catalog/11695521.