MLA

Watkins, Carleton E., 1829-1916. Stockton Creek. Folder 19. [ca. 1860-1861]. https://collections.library.yale.edu/catalog/2017952.

APA, 6th edition

Watkins, Carleton E., 1829-1916. (["Folder 19"])([ca. 1860-1861])[Stockton Creek]. https://collections.library.yale.edu/catalog/2017952.