1. 1) N. Arbiter and A. W. Fletcher : Hydrometallurgy --- Fundamentals, Technology, and Innovations, (Edited by J. B. Hiskey and G. W. Warren, Society for Mining, Metallurgy, and Exploration, Inc., Littleton, Colorado, 1993) , pp. 549-565.
2. 2) P. K. Everett and A. J. Moyes : Extractive Metallurgy of Gold and Base Metals, (Edited by V. Misra, D. Halbe and D. J. Spottiswood, The Australasian Institute of Mining and Metallurgy, Carlton Victoria, 1992) , pp. 287-292.
3. 3) N. Masuko : Denki Kagaku, 27 (1959) , 365-374.
4. 4) N. Masuko and T. Hisamatsu : Kinzoku, 25 (1959) , 385-389.
5. 5) W. M. Latimer : The Oxidation States of the Elements and their Potentials in Aqueous Solutions, 2nd Ed. (Prentice-Hall, New York, 1952) .