1919. Cowen, Clinton. Scale approximately 1:126,720. 1 in. = 2 miles. Scale approximately 1:88,000. 1 in. = 4 miles. "Copyright 1919 by Clinton Cowen, State Highway Comm... Printing Commission of Ohio.
2003. Ohio. Division of Geological Survey. Relief shown by shading and gradient tints. Map of geologic regions, with text, on verso. Scale 1:2,000,000. Ohio. Division of Geological Survey.