MLA

Sully, Alfred, 1821-1879. Correspondence. Box 1, folder 17. 1861. https://collections.library.yale.edu/catalog/16703587.

APA, 6th edition

Sully, Alfred, 1821-1879. (["Box 1, folder 17"])(1861)[Correspondence]. https://collections.library.yale.edu/catalog/16703587.