1. D.W. Hopkins: Bull. Inst. Min. Metall., 1949, vol. 515, pp. 1–21
2. G.G. Graf: Ullmann’s Encyclopedia of Industrial Chemistry, 7th ed., Wiley Interscience, New York, NY, 2005, pp. 1–23
3. G.A. Komlev, V.N. Gareev: Tsv. Met. (Moscow), 1964, vol. 37 (3), pp. 22–29
4. C.Y. Choi, Y.H. Lee: REWAS ‘99—Global Symp. on Recycling, Waste Treatment and Clean Technology, TMS, Warrendale, PA, 1999, pp. 1613–22
5. P.C. Holloway, T.H. Etsell: EPD Congress 2006, TMS, Warrendale, PA, 2006, pp. 525–34