MLA

Heath, William, 1795-1840, printmaker. Rats in the barn, or, Iohn Bulls famous old dog Billy astonishing the varment [graphic]. [ca. March 1829]. https://collections.library.yale.edu/catalog/15810042.

APA, 6th edition

Heath, William, 1795-1840, printmaker. ([ca. March 1829])[Rats in the barn, or, Iohn Bulls famous old dog Billy astonishing the varment [graphic]]. https://collections.library.yale.edu/catalog/15810042.