MLA

Bourlier, Mary Ann, and printmaker. Her Royal Highness the Duchess of York [Graphic]. Published by E. Harding, 19AD. https://collections.library.yale.edu/catalog/33191982.

APA, 6th edition

Bourlier, M. A., & printmaker. (19 C.E.). Her Royal Highness the Duchess of York [graphic] [Portrait prints, Stipple engravings England London 1806]. Published by E. Harding. https://collections.library.yale.edu/catalog/33191982.