1. Branch, S.J., Byron, D.J., Gray, G.W., Ibbotson, A., Worrall, B.M.: J. Chem. Soc. 3279 (1964).
2. Kobayashi, S., Ishibashi, S., Horie, T., Tsuru, S., Nakamura, K., Manmo, T. (Nippon Telegraph and Telephone): EP 315.193 (4.11.88) ; JP 87280.456 (6.11.87) ; JP 280.458 (6.11.87) ; JP 88-136.792 (3.6.88) ; JP …(1989).
3. Mauerhoff, E.: Ph. D. Thesis Halle (1922).
4. Byron, D.J., Gray, G.W., Worrall, B.M.: J. Chem. Soc. 3706 (1965).
5. Wen, J., Xu, Y., Tian, M., Chcn, Q.: Fcrroclectrics 148,129 (1993).