MLA

[Maria Walpole] [Art Original]. 0AD. https://collections.library.yale.edu/catalog/15815188.

APA, 6th edition

[Maria Walpole] [art original]. (0 C.E.). [Miniatures (Paintings), Paintings British 18th century, Portraits British 18th century, Watercolors British 18th century]. https://collections.library.yale.edu/catalog/15815188.