MLA

Whitman, Walt, 1819-1892. Unidentified. Box 4, folder 183. 1864-85, n.d.. https://collections.library.yale.edu/catalog/2053814.

APA, 6th edition

Whitman, Walt, 1819-1892. (["Box 4, folder 183"])(1864-85, n.d.)[Unidentified]. https://collections.library.yale.edu/catalog/2053814.