1. J. L. Snoek, in ?New developments in Ferro-magnetic Materials? (Elsevier, Amsterdam, 1947) p. 99.
2. Permanent Magnet Association, Sheffield, England, private communication.
3. T. Mishima, British Patent, 718 736 (1952).
4. I. Briggs andA. G. Clegg,IEEE Trans. Magnetics MAG-20 (1984) 1628.
5. R. Oshima andC. M. Wayman,Metall. Trans. 3 (1972) 2163.