Cite

Powder Face. Arapahoe chief in full war dress

MLA

Powder Face. Arapahoe Chief in Full War Dress. William Soule, 0AD. https://collections.library.yale.edu/catalog/2010394.

APA, 6th edition

Powder Face. Arapahoe chief in full war dress. (0 C.E.). [Photographic prints, Photographs]. William Soule. https://collections.library.yale.edu/catalog/2010394.