MLA

Optimus Britons Behold the Best of Kings. [Graphic]. To be had at the Acorn facing Hungerford, Strand, 0AD. https://collections.library.yale.edu/catalog/10714608.

APA, 6th edition

Optimus Britons behold the best of kings. [graphic]. (0 C.E.). [Satires England 1756, Portrait prints, Engravings England London 1756, Etchings England London 1756, Book illustrations]. To be had at the Acorn facing Hungerford, Strand. https://collections.library.yale.edu/catalog/10714608.