1. Physiographic and land use characteristics associated with nitrate-nitrogen in Montana ground water;Bauder;Journal of Environmental Quality,1993
2. Montana extension initiative focuses on private well quality;Bauder;Journal of Soil and Water Conservation,1991
3. Briar , D.W. J.P. Madison 1992 Hydrogeology of the Helena valley-fill aquifer system, west-central Montana U.S. Geological Survey
4. Census and Economic Information Center 2003 Demographics Montana Department of Commerce http://ceic.commerce.state.mt.us/Demog/1990dec/8090cty.pdf