Author
Geological Survey (U.S.),
6
Brock, M. R. 1922-
1
Currier, L. W. 1890-1970,
1
Fenneman, Nevin Melancthon, 1865-1945,
1
Heyl, Allen V. 1918-2008,
1
Illinois State Geological Survey
1
Jolly, J. L.,
1
Pinckney, Darrell M.,
1
Rubey, William Walden, 1898-1974,
1
Udden, Johan August, 1859-1932,
1
Wells, C. E.,
1