MLA

McClintock, Walter, 1870-1949. 211. [Home Land of Siksikaikoan (Little Blackfoot)/William Jackson and His Family. Divide Mountain in the Center Background.]. Box 61, folder 3040. 1938. https://collections.library.yale.edu/catalog/2008484.

APA, 6th edition

McClintock, Walter, 1870-1949. (["Box 61, folder 3040"])(1938)[211. [Home Land of Siksikaikoan (Little Blackfoot)/William Jackson and His Family. Divide Mountain in the Center Background.]]. https://collections.library.yale.edu/catalog/2008484.