a. correspondence with A. R. Chapin regarding Chapin’s disagreement with selected points in Sitting Bull, 1932.
b. a newsletter from Houghton Mifflin Company which includes an article regarding Sitting Bull’s signature on the cover of Sitting Bull, 1932.
c. correspondence from Campbell regarding a negative review of Sitting Bull, 1933.
d. a list of articles Campbell is willing sell to the Oklahoma Historical Society, 1935.
e. correspondence with Rudolph Cronau regarding praise of Sitting Bull, 1936.
f. correspondence with Mrs. H. O. Cypert regarding Sitting Bull’s genealogy, 1952-1953.
g. general research correspondence “C,” 1935-1953.