Leitner, J. “The Political Economy of Raw Materials Transport from Internal Periphery to Core in the Early 20th Century US: The Calumet & Hecla Copper Company?S Struggle for Market Access, 1922?39”. Journal of World-Systems Research, vol. 10, no. 2, Aug. 2004, pp. 397-35, doi:10.5195/jwsr.2004.294.