- Geological Survey (U.S.)
- University of Illinois at Urbana-Champaign, University Library
Relief shown by contours and spot heights.; "Mapped by the Geological Survey 1946"; "Contour interval 20 feet."; Shows roadway classification as of 1947.; Coordinates: (W 91⁰15ʹ00ʺ--W 91⁰00ʹ00ʺ/N 41⁰30ʹ00ʺ--N 41⁰15ʹ00ʺ). 45 x 34 cm.; 1 map, colored. 1:62,500. Geological Survey (U.S.); Geological Survey Division (Urbana, Ill.).