1. 1) J. Shibata and A. Okuda: J. MMIJ 118(2002) 1-8.
2. 2) M. Cox: Principles and Practices of Solvent Extraction. 2nd ed. (Marcel Dekker, Inc., New York, 2004) pp. 455-505.
3. 3) F. K. Crundwell, M. S. Moats, V. Ramachandran, T. G. Robinson and W. G. Davenport: Extractive Metallurgy of Nickel, Cobalt and Platinum Group Metals, (Elsevier, Oxford, 2011).
4. 4) M. Tanaka: J. MMIJ 113(1997) 940-944.
5. 5) Y. Ueda and K. Ohto: Bunseki 492(2015) 534-544.