MLA

Vertue, George, 1684-1756, printmaker. Sara illustrissima Ducissa Somersetensis ex gente Alstoniana in agro Bedfordiensi / [graphic]. [1736?]. https://collections.library.yale.edu/catalog/15960341.

APA, 6th edition

Vertue, George, 1684-1756, printmaker. ([1736?])[Sara illustrissima Ducissa Somersetensis ex gente Alstoniana in agro Bedfordiensi / [graphic]]. https://collections.library.yale.edu/catalog/15960341.