MLA

Kay, John, 1742-1826, printmaker. Two shadows in conversation [graphic]. [1788, i.e., not before 1877]. https://collections.library.yale.edu/catalog/15810066.

APA, 6th edition

Kay, John, 1742-1826, printmaker. ([1788, i.e., not before 1877])[Two shadows in conversation [graphic]]. https://collections.library.yale.edu/catalog/15810066.