MLA

Hitchcock, Ethan Allen, 1798-1870. Seminole. Box 3, folder 10. 1837-1838, undated. https://collections.library.yale.edu/catalog/16717220.

APA, 6th edition

Hitchcock, Ethan Allen, 1798-1870. (["Box 3, folder 10"])(1837-1838, undated)[Seminole]. https://collections.library.yale.edu/catalog/16717220.