- Geological Survey (U.S.)
- University of Illinois at Urbana-Champaign, University Library
Relief shown by contours and spot heights.; "Surveyed in 1919 and 1921."; "Surveyed in cooperation with the State of Illinois."; "Contour interval 20 feet. 45 x 36 cm.; 1 map, colored. 1:62,500. Geological Survey (U.S.); Geological Survey Division (Urbana, Ill.).