MLA

Whitman, Walt, 1819-1892. S.[amuel] Hollyer engravings. Box 11, folder 233. [1855]. https://collections.library.yale.edu/catalog/2053858.

APA, 6th edition

Whitman, Walt, 1819-1892. (["Box 11, folder 233"])([1855])[S.[amuel] Hollyer engravings]. https://collections.library.yale.edu/catalog/2053858.