a. correspondence from Charles N. Gould, Oklahoma Geological Survey, regarding C. F. Colcord, Fred Sutton, and J. B. Thoburn, 1928.b. correspondence with James H. Cook regarding Red Cloud and Sitting Bull, 1928.
c. correspondence from E. A. Garlington regarding Sitting Bull, 1929.
d. correspondence from W. J. Ghent regarding his sketch and bibliography of Sitting Bull, 1929.
e. correspondence with Henry N. Graven regarding his father, T. J. Thompson, 1930.
f. correspondence from Campbell to Houghton Mifflin asking for an advance on Sitting Bull of $400.00, June, 1931.
g. general research correspondence “G,” 1928-1945.