MLA

Bentley, R. (Richard), 1708-1782, artist. Gateway for Strawberry Hill by Mr. Bentley [art original].. [not after 1760]. https://collections.library.yale.edu/catalog/16873184.

APA, 6th edition

Bentley, R. (Richard), 1708-1782, artist. ([not after 1760])[Gateway for Strawberry Hill by Mr. Bentley [art original].]. https://collections.library.yale.edu/catalog/16873184.