Cite

The modern Hercules destroying the Hydra of fanaticism [graphic]

MLA

Kay, John, 1742-1826, printmaker. The modern Hercules destroying the Hydra of fanaticism [graphic]. [1789]. https://collections.library.yale.edu/catalog/17288804.

APA, 6th edition

Kay, John, 1742-1826, printmaker. ([1789])[The modern Hercules destroying the Hydra of fanaticism [graphic]]. https://collections.library.yale.edu/catalog/17288804.