Smith, Robert W.Base map by U.S. Geological Survey.compiled by Robert W. Smith.Scale 1:500,000 ; Lambert conformal conic projectionTIFFhttps://hdl.handle.net/1811/75d4eaad-d47f-4dcd-8fe5-9cab2a0078cbengOhio. Division of Geological SurveyPublicMineral industriesMineral industry map of Ohio, 1956MapsOhioThe Ohio State University