1. U.S. Department of Energy. Energy Information and Administration, 2010, Short term energy look, August 10.http://www.eia.doe.gov/steo/archives/aug10.pdf
2. U.S. Department of Energy. Energy Information and Administration, 2011, Short term energy outlook, April 12,http://www.eia.doe.gov/steo/#Coal
3. U.S. Department of Energy. Energy Information and Administration, 2004, Coal Transportation rate database, September 17.http://www.eia.doe.gov/cneaf/coal/page/trans/ratesntrends.html