TY - BOOK AU - Young,H.L. TI - Summary of ground-water hydrology of the Cambrian-Ordovician aquifer system in the northern Midwest, United States T2 - U.S. Geological Survey professional paper U1 - 551.490977 PY - 1992/// CY - Washington PB - U.S. G.P.O. KW - Groundwater KW - Middle West KW - Aquifers KW - Geology, Stratigraphic KW - Cambrian KW - Ordovician ER -