MLA

Speck, William A. (William Alfred), 1864-1928. Autograph note. Box 12, folder 465. 1785 Feb 15. https://collections.library.yale.edu/catalog/17266945.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 12, folder 465"])(1785 Feb 15)[Autograph note]. https://collections.library.yale.edu/catalog/17266945.