A, [400]. [Map of the United States of America that Shows the Four Reservations or Restricted Country of the Blackfeet.]
MLA
McClintock, Walter, 1870-1949. A, [400]. [Map of the United States of America that Shows the Four Reservations or Restricted Country of the Blackfeet.]. Box 61, folder 3027. 1938. https://collections.library.yale.edu/catalog/2008472.
APA, 6th edition
McClintock, Walter, 1870-1949. (["Box 61, folder 3027"])(1938)[A, [400]. [Map of the United States of America that Shows the Four Reservations or Restricted Country of the Blackfeet.]]. https://collections.library.yale.edu/catalog/2008472.
