Cite

Humphrey, Duke of Gloucester [art original].

MLA

Carter, John, 1748-1817, artist. Humphrey, Duke of Gloucester [art original].. [approximately 1790]. https://collections.library.yale.edu/catalog/16733118.

APA, 6th edition

Carter, John, 1748-1817, artist. ([approximately 1790])[Humphrey, Duke of Gloucester [art original].]. https://collections.library.yale.edu/catalog/16733118.