MLA

McClintock, Walter, 1870-1949. FS-162. Painting by Clarence Ellsworth of White Grass.. Box 147, folder 7868. 1947 September. https://collections.library.yale.edu/catalog/10453482.

APA, 6th edition

McClintock, Walter, 1870-1949. (["Box 147, folder 7868"])(1947 September)[FS-162. Painting by Clarence Ellsworth of White Grass.]. https://collections.library.yale.edu/catalog/10453482.