MLA

Bonnor, Thomas. King Edward the Second's Monument in Gloucester Cathedral [Graphic]. Publish'd according to act of Parliament August 1st 1780 by Ralph Bigland, Garter principal King of Arms, 0AD. https://collections.library.yale.edu/catalog/16194615.

APA, 6th edition

Bonnor, T. (0 C.E.). King Edward the Second's monument in Gloucester Cathedral [graphic] [Engravings England London 1780, Watermarks (Paper) J. Whatman 1794]. Publish'd according to act of Parliament August 1st 1780 by Ralph Bigland, Garter principal King of Arms. https://collections.library.yale.edu/catalog/16194615.