MLA

Kay, John, 1742-1826, printmaker. Willm. Wilson commonly called Mortar Willie aged 107 [graphic]. 1815 i.e. not before 1842]. https://collections.library.yale.edu/catalog/10967851.

APA, 6th edition

Kay, John, 1742-1826, printmaker. (1815 i.e. not before 1842])[Willm. Wilson commonly called Mortar Willie aged 107 [graphic]]. https://collections.library.yale.edu/catalog/10967851.