Cite

[Portrait of Horatio Walpole, 2nd Baron ('Pigwiggin') Walpole] [art original].

MLA

Walton, Henry, 1746-1813, artist. [Portrait of Horatio Walpole, 2nd Baron ('Pigwiggin') Walpole] [art original].. [not after 1813]. https://collections.library.yale.edu/catalog/33111561.

APA, 6th edition

Walton, Henry, 1746-1813, artist. ([not after 1813])[[Portrait of Horatio Walpole, 2nd Baron ('Pigwiggin') Walpole] [art original].]. https://collections.library.yale.edu/catalog/33111561.