1. C. G. Whinfreg, D. W. Eckart andA. Tauber,J. Amer. Chem. Soc. 82 (1960) 2695.
2. T. Takada andM. Kiyama, in Proceedings of the International Conference on Ferrites, Japan 1970 pp. 69–71.
3. T. Yamaguchi andT. Nomura,ibid., Japan, 1980, pp. 46–9.
4. P. J. Slick in “Ferromagnetic Materials” Vol. 2, edited by E. P. Wohlfarth (Amsterdam 1980) pp. 204–8.
5. N. Burriesci, F. Garbassi andS. Pizzini,J. Magn. Magn. Mat. 7 (1978) 52.