1. Association of American Railroads.2014.Railroads and Ethanol.https://www.aar.org/keyissues/Documents/Background‐Papers/Railroads%20and%20Ethanol.pdf. May.
2. Did Railroads Induce or Follow Economic Growth? Urbanization and Population Growth in the American Midwest, 1850–1860;Atack J.;Social Science History,2010
3. 2004 Nortons New York J. Atack P. Passell A New Economic View of American History