1934. Geological Survey (U.S.). Surveyed in 1931 and 1932.; (W 90⁰15’00"--W 90⁰00’00"/N 41⁰30’00"--N 41⁰15’00");Culture and drainage in part compiled from aerial photographs taken... Geological Survey (U.S.)|Geological Survey Division (Urbana, Ill.).