1. A. N. Zelikman, O. E. Krein and G. V. Samsonov, Metallurgy of Rare Metals, Metallurgia Publ., Moscow 1964.
2. F. M. Luskotov, Metallurgy of Lead & Zinc, Metallurg. Izdat, 1965.
3. C. Palache, H. Berman and C. Frondel, Dana's System of Mineralogy, 7th Ed., New York, Wiley, Vol. 2, 1962.
4. Wm. R. Phillips and D. T. Griffen, Optical Mineralogy. The Nonopaque Minerals, W. H. Freeman and Company, 1981.
5. A. M. Abdel Rehim, Application of Thermal Analysis in Mineral Technology, Thermal Analysis in Geosciences, Vol. 38, (Eds.) W. Smykatz-Kloss & S. St. J. Warne, Springe-Verlag, 1991, p. 188.