1. T. Takeshita and R. Nakayama, Proc. 10th Int. Workshop on Rare Earth Magnets and their Applications, Kyoto, 1989, p. 551.
2. I.R. Harris, Proc. 12th Int. Workshop on Rare-Earth Magnets and their Applications, Canberra, 1992, p. 347.
3. S. Sugimoto, H. Nakamura, M. Okada and M. Homma, Proc. 12th Int. Workshop on Rare-Earth Magnets and Their Applications, Canberra, 1992, p. 372.
4. C.E. Messer and M.K. Park, J. Less-Common Metals, 26 (1972) 235.
5. C. Ohki, H. Uchida and E. Ko, J. Japan Inst. Metals, 54 (1990) No. 2, 146.