MLA

Woodward, G. M. (George Moutard), approximately 1760-1809, artist. [Manservant wearing an apron] [art original]. [approximately 1790]. https://collections.library.yale.edu/catalog/10731191.

APA, 6th edition

Woodward, G. M. (George Moutard), approximately 1760-1809, artist. ([approximately 1790])[[Manservant wearing an apron] [art original]]. https://collections.library.yale.edu/catalog/10731191.