United States Geological Survey (USGS). "United States Geological Survey Topographic Map". TopoQuest. Retrieved December 9, 2012. Map quadrangles show river mileage for the first 26 miles (42 km) of the lower main stem. The remaining distance is an estimate based on map scale and ruler.
usda.gov
fs.usda.gov
"Elk River". U.S. Forest Service. Retrieved December 9, 2012.