MLA

Gibbs, J. Willard (Josiah Willard), 1839-1903. Autograph letter, signed, (draft) to Henri Louis Le Chatelier. New Haven.. Box 1, folder 7. 1899 October 28. https://collections.library.yale.edu/catalog/17296909.

APA, 6th edition

Gibbs, J. Willard (Josiah Willard), 1839-1903. (["Box 1, folder 7"])(1899 October 28)[Autograph letter, signed, (draft) to Henri Louis Le Chatelier. New Haven.]. https://collections.library.yale.edu/catalog/17296909.