1. F.W. Davis, The Use of Oxygen or Oxygenated Air in Metallurgical and Allied Processes, Report of Investigations no. 2502 (Washington, D.C.: Bureau of Mines, July 1923).
2. Rachel Carson, Silent Spring (New York: Houghton Mifflin, 1962).
3. Paul E. Queneau, “The Recovery of Nickel from Its Ores,” JOM, 22 (10) (1970).
4. Fred Kaplan, “Norilsk, Russia, Mining and Metallurgical Works,” The Boston Globe (17 November 1994).
5. T.E. Norman, Eng. and Min. J., (10-11) (1936), p. 137.