1916. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1913-1914.";"Surveyed in cooperation with the State of Illinois.";Coordinates (W 88⁰30’00"--W 88⁰15’00"/N 37... Geological Survey (U.S.) and State of Illinois State Geological Survey (Urbana, Ill.).
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1916. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1913.";"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heights.;1 ma... Geological Survey (U.S.) and State Geological Survey (Urbana, Ill.).
1916. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1913.";"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heights.;1 ma... Geological Survey (U.S.) and State Geological Survey (Urbana, Ill.).
1916. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1890.";Relief shown by contours.;1 map, colored;45 x 34 cm.;1:62,500. Geological Survey (U.S.).
1916. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1910 and 1914.";"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heig... Geological Survey (U.S.) and Geological Survey Division (Urbana, Ill.).