a. correspondence with H. L. Davis regarding Indian methods of warfare, 1933.
b. correspondence with Alfred Powell regarding the Cheyenne Dog Soldiers, 1942-1943.
c. correspondence with Don Russell regarding the reliability of Indians as warriors and army scouts, 1956.
d. Research materials regarding Indian warriors correspondence with Jack Spears regarding Campbell’s help on an article about how Indians have been depicted in films, 1957.