MLA

Amateurs in Music Sounding Their A [Graphic]. Pubd. April 21, 1794, by S.W. Fores, No. 3 Piccadilly, 0AD. https://collections.library.yale.edu/catalog/10939048.

APA, 6th edition

Amateurs in music sounding their A [graphic]. (0 C.E.). [Satires (Visual works) England 1794, Etchings England London 1794]. Pubd. April 21, 1794, by S.W. Fores, No. 3 Piccadilly. https://collections.library.yale.edu/catalog/10939048.