References
- Chen , Z. Y. and Walker , M. B. 1990 . Phys. Rev. Lett. , 65 : 1223
- Chen , Z. Y. and Walker , M. B. 1991 . Phys. Rev. , B43 : 5634
- Chen , Z. Y. and Walker , M. B. 1991 . Phys. Rev. , B43 : 760
- Folkins , Ian , Walker , M. B. and Chen , Z. Y. to be published in Physical Review
- Tentrup , T. and Siems , R. 1990 . Ferroelectrics , 105 : 379
- Janssen , T. 1986 . Ferroelectrics , 66 : 203
- Ueda , T. , Iida , S. and Terauchi , H. 1982 . J. Phys. Soc. Jpn. , 51 : 3953