MLA

Dennistoun, James, 1803-1855. Hamilton, William Alexander Anthony Archibald Hamilton, 11th Duke of, 1811-1863. ALS to James Dennistoun, Hamilton Palace. Box 3, folder 92. 1842 Dec 10. https://collections.library.yale.edu/catalog/16683949.

APA, 6th edition

Dennistoun, James, 1803-1855. (["Box 3, folder 92"])(1842 Dec 10)[Hamilton, William Alexander Anthony Archibald Hamilton, 11th Duke of, 1811-1863. ALS to James Dennistoun, Hamilton Palace]. https://collections.library.yale.edu/catalog/16683949.