MLA

Seymour, Samuel. Kaskaia, Shienne Chief, Arrappaho. 1819. https://collections.library.yale.edu/catalog/2001465.

APA, 6th edition

Seymour, S. (1819). Kaskaia, Shienne Chief, Arrappaho [Group portraits, Watercolors (Paintings)]. https://collections.library.yale.edu/catalog/2001465.