MLA

Illman, and engraver Sons. Gen. Zachary Taylor. s.n., 1846. https://collections.library.yale.edu/catalog/2016157.

APA, 6th edition

I., & Sons, engraver. (1846). Gen. Zachary Taylor [Portraits, Mezzotints]. s.n. https://collections.library.yale.edu/catalog/2016157.