MLA

McClintock, Walter, 1870-1949. FS-158. Painting by Clarence Ellsworth of Spotted Eagle.. Box 147, folder 7863. 1946 August. https://collections.library.yale.edu/catalog/10453478.

APA, 6th edition

McClintock, Walter, 1870-1949. (["Box 147, folder 7863"])(1946 August)[FS-158. Painting by Clarence Ellsworth of Spotted Eagle.]. https://collections.library.yale.edu/catalog/10453478.