U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArkivigite je 2017-08-23 per la retarkivo Wayback Machine, accessed Aprilo 1a, 2011
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U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArkivigite je 2017-08-23 per la retarkivo Wayback Machine, accessed Aprilo 1a, 2011