"Wells Standards." . . . . "GROUNDWATER." . . "United States. Environmental Protection Agency. Office of Water Supply." . . "National Water Well Association." . . "RESOURCES EXPLORATION." . . "WELL DRILLING." . . . . . . . . . . . . . . . . . . . . "Manual of water well construction practices" . "Manual of water well construction practices"@en . . . . . . . . . .