1. Nitrate concentrations in ground water in the paleovalley alluvial aquifers of the Nemaha Natural Resources District, Nebraska, 1989 and 1994-96 Author/Creator: Chen, Abraham H., author Publication/Creation: Lincoln, Nebraska : U.S. Geological Survey, 1998 Resource Type: Book Access & Availability: Loading
2. Nonpoint-source agricultural chemicals in ground water in Nebraska : preliminary results for six areas of the High Plains aquifer Author/Creator: Chen, Hsiu-Hsiung, 1937- author Publication/Creation: Lincoln, Nebraska : U.S. Geological Survey, 1987 Resource Type: Book Access & Availability: Loading