Cite

[Portrait of Horace Walpole, 4th Earl of Orford] [art original].

MLA

Ramsay, Allan, 1713-1784, artist. [Portrait of Horace Walpole, 4th Earl of Orford] [art original].. [not after 1784]. https://collections.library.yale.edu/catalog/16731045.

APA, 6th edition

Ramsay, Allan, 1713-1784, artist. ([not after 1784])[[Portrait of Horace Walpole, 4th Earl of Orford] [art original].]. https://collections.library.yale.edu/catalog/16731045.