MLA

Ely, William Davis, 1815-1908. Ely, Richard Sheldon. Box 1, folder 5. 1837. https://collections.library.yale.edu/catalog/32532143.

APA, 6th edition

Ely, William Davis, 1815-1908. (["Box 1, folder 5"])(1837)[Ely, Richard Sheldon]. https://collections.library.yale.edu/catalog/32532143.