MLA

Clark, William, 1770-1838. Map from "Sundery Indians of the Chopunnish Nation together" on May 29, 30, and 31, 1806, at "our Camp on the Flat Head River". Box 2, folder 56r. circa 1803-1810. https://collections.library.yale.edu/catalog/2002509.

APA, 6th edition

Clark, William, 1770-1838. (["Box 2, folder 56r"])(circa 1803-1810)[Map from "Sundery Indians of the Chopunnish Nation together" on May 29, 30, and 31, 1806, at "our Camp on the Flat Head River"]. https://collections.library.yale.edu/catalog/2002509.