MLA

Whitman, Walt, 1819-1892. Major & Knapp Engraving, Manufacturing & Lithographic Co.. Box 4, folder 180. 1879-85, n.d.. https://collections.library.yale.edu/catalog/2053811.

APA, 6th edition

Whitman, Walt, 1819-1892. (["Box 4, folder 180"])(1879-85, n.d.)[Major & Knapp Engraving, Manufacturing & Lithographic Co.]. https://collections.library.yale.edu/catalog/2053811.