MLA

[Sarah Siddons] [Graphic]. publisher not identified, 0AD. https://collections.library.yale.edu/catalog/10986864.

APA, 6th edition

[Sarah Siddons] [graphic]. (0 C.E.). [Portrait prints, Crayon manner prints England London 1775]. publisher not identified. https://collections.library.yale.edu/catalog/10986864.