MLA

Whitman, Walt, 1819-1892. Galley proof. Box 3, folder 163. 1889. https://collections.library.yale.edu/catalog/2053795.

APA, 6th edition

Whitman, Walt, 1819-1892. (["Box 3, folder 163"])(1889)[Galley proof]. https://collections.library.yale.edu/catalog/2053795.