MLA

Eliot, George, 1819-1880. Letter, Thursday, to Mrs. Bray. Box 1. [1853 Dec 29]. https://collections.library.yale.edu/catalog/32366209.

APA, 6th edition

Eliot, George, 1819-1880. (["Box 1"])([1853 Dec 29])[Letter, Thursday, to Mrs. Bray]. https://collections.library.yale.edu/catalog/32366209.