MLA

Proteus [the] 2d in Sev'Ral among His Many Publick Characters [Graphic]. Pubd. as the act directs 178[...] by B. Pownall, No. 6 Pall Mall, 0AD. https://collections.library.yale.edu/catalog/10724792.

APA, 6th edition

Proteus [the] 2d in sev'ral among his many publick characters [graphic]. (0 C.E.). [Satires (Visual works) England 1783, Etchings England London 1783]. Pubd. as the act directs 178[...] by B. Pownall, No. 6 Pall Mall. https://collections.library.yale.edu/catalog/10724792.