MLA

An Appeal to Britons [Graphic]. Pub. Aug. 23, 1820, by S.W. Fores, 41 Picadilli [sic], 0AD. https://collections.library.yale.edu/catalog/33245806.

APA, 6th edition

An appeal to Britons [graphic]. (0 C.E.). [Caricatures and cartoons, Caricatures England 1820, Satires (Visual works) England 1820, Etchings England London 1820, Annotations (Provenance) 19th century, Watermarks (Paper) Weatherley & Lane 1818]. Pub. Aug. 23, 1820, by S.W. Fores, 41 Picadilli [sic]. https://collections.library.yale.edu/catalog/33245806.