1. 1) R. O’Connell, C. Alexander, R. Strachan, B. Always, S. Nambiath, J. Wiebe, L. Wong, E. Rannestad, S. Li, D. Aranda and N. Scott-Gray, “GFMS PLATINUM GROUP METALS SURVEY 2017” Thomson Reuters, London (2017).
2. 2) Y. Kondo, M. Kubota and T. Abe, K. Nagato, JAERI-M 91-147 (1991) [in Japanese].
3. 3) R.P. Bush, Platinum Metals Rev., 35, 202 (1991).
4. 4) Z. Kolarik and E.V. Renard, Platinum Metals Rev., 47, 74 (2003).
5. 5) Y. Ando and H. Takano, JAERI-Research 99-004 (1999) [in Japanese].