MLA

Eliot, George, 1819-1880. Letter. Box 11. 1944 Jun 24. https://collections.library.yale.edu/catalog/10001577.

APA, 6th edition

Eliot, George, 1819-1880. (["Box 11"])(1944 Jun 24)[Letter]. https://collections.library.yale.edu/catalog/10001577.