Hydrogeology of the Cambrian-Ordovician aquifer system in the northern Midwest, United States - Young, H. L.; Siegel, Donald I.; Geological Survey (U.S.) (Washington : U.S. G.P.O., 1992)
1 col. map in pocket
Keywords: Groundwater -- Middle West; Aquifers -- Middle West; Geology, Stratigraphic -- Cambrian; Geology, Stratigraphic -- Ordovician