MLA

Gilbert, Z. (Zalmon), artist. Gray Bear, Wife, and Pappoose. ca. 1880. https://collections.library.yale.edu/catalog/2009500.

APA, 6th edition

Gilbert, Z. (Zalmon), artist. (ca. 1880)[Gray Bear, Wife, and Pappoose]. https://collections.library.yale.edu/catalog/2009500.