1. A.R. Burkin: Extractive Metallurgy of Nickel, Society of Chemical Industry, John Wiley & Sons, Great Britain, 1987, p. 9.
2. T. Mäkinen: Espoo, Finland U.S. Patent 5332414, July 26, 1994.
3. T. Mäkinen and P. Taskinen: in Sulfide Smelting’ 98: Current and Future Practices, J.A. Asteljoki and R.L. Stephens, eds., TMS, Warrendale, PA, 1998, pp. 59–68.
4. M. Nagamori and P.J. Mackey: Metall. Trans. B, 1978, vol. 9B, pp. 255–65.
5. M. Nagamori and P.C. Chaubal: Metall. Trans. B, 1982, vol. 13B, pp. 319–29 and 331–38.