References
- Cubane , B. and Friedel , J. 1971 . J. Phys., Paris , 32 : 73
- Cutler , M. 1971a . Phil. Mag. , 24 : 381
- 1971b . Phil. Mag. , 24 : 401
- 1974 . Phys. Rev. B , 15 : 693
- Enderby , J. E. and Gay , M. 1980 . J. non-crystalline Solids , 35 : 1269
- Gardner , J. A. and Cutler , M. 1976 . Phys. Rev. B , 14 : 4488
- Gay , M. , Enderby , J. E. and Copestake , A. P. 1982 . J. Phys. C , 15 : 4641
- Robertson , J. 1979 . Phil. Mag. B , 39 : 501
- 1981 . Phil. Mag. B , 44 : 239
- Vanderbilt , D. L. and Joannopoulos , J. D. 1979 . Phys. Rev. Lett. , 42 : 1012