MLA

The Principal Merchants & Traders Assembled at the Merchant Seaman's Office to Sign [the] Address [Graphic]. publisher not identified, 0AD. https://collections.library.yale.edu/catalog/10713407.

APA, 6th edition

The principal merchants & traders assembled at the Merchant Seaman's Office to sign [the] address [graphic]. (0 C.E.). [Satires (Visual works) England 1769, Etchings England London 1769, Periodical illustrations]. publisher not identified. https://collections.library.yale.edu/catalog/10713407.