U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArkivert 2012-04-05 hos WebCite, accessed May 13, 2011
webcitation.org
U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArkivert 2012-04-05 hos WebCite, accessed May 13, 2011