Markstrom, Steven L, Niswonger, Richard G, Regan, R Steven, Prudic, David E, and Barlow, Paul M, 2008, GSFLOW - Coupled Ground-Water and Surface-Water Flow Model Based on the Integration of the Precipitation-Runoff Modeling System (PRMS) and the Modular Ground-Water Flow Model (MODFLOW-2005): Geological Survey (U.S.).