- Geological Survey (U.S.)
- University of Illinois at Urbana-Champaign, University Library
Relief indicated by contours and spot heights.; "Surveyed in 1906-1907."; "Surveyed in cooperation with the State of Illinois."; "Contour interval 10 feet."; Coordinates: (W 90⁰00ʹ00ʺ--W 89⁰45ʹ00ʺ/N 40⁰00ʹ00ʺ--N 39⁰45ʹ00ʺ). 45 x 34 cm.; 1 map, colored. 1:62,500. Geological Survey (U.S.); Geological Survey Division (Urbana, Ill.).