MLA

Scott, William Bell, 1811-1890. Letter : to Algernon Charles Swinburne. GROUP 456, folder F-3. [1865]. https://collections.library.yale.edu/catalog/16666355.

APA, 6th edition

Scott, William Bell, 1811-1890. (["GROUP 456, folder F-3"])([1865])[Letter : to Algernon Charles Swinburne]. https://collections.library.yale.edu/catalog/16666355.