1917. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1914.";"Surveyed in cooperation with the State of Illinois.";Relief indicated by contours and spot heights.;... Geological Survey (U.S.) and State Geological Survey (Urbana, Ill.).
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1917. Geological Survey (U.S.). Surveyed in 1914.;"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heights.;1 map, colored;45 x 35 cm.;1:62,500. Geological Survey (U.S.) and Geological Survey Division (Urbana, Ill.).
1917. Geological Survey (U.S.). Surveyed in 1914-1915.;"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heights.;1 map, colored;45 x 36 cm.;... Geological Survey (U.S.) and Geological Survey Division (Urbana, Ill.).