MLA

Eliot, George, 1819-1880. Letter. Box 7. [1885] Apr 22. https://collections.library.yale.edu/catalog/32368850.

APA, 6th edition

Eliot, George, 1819-1880. (["Box 7"])([1885] Apr 22)[Letter]. https://collections.library.yale.edu/catalog/32368850.