References
- Mc Millan , W. L. 1976 . Phys. Rev. B , 14 : 1496
- Rice , T. M. and Littlewood , P. 1982 . Phys. Rev. Lett. , 48 : 44
- Prelovsek , P. and Rice , T. M. to be published
- Ishibashi , Y. 1980 . Ferroelectrics , 24 : 119
- Prelovsek , P. and Blinc , R. to be published