1. N. J. Doran, Physica 99B, 227 (1980).
2. C. Y. Fong and M. Schlüter in Electrons and Phonons in Layered Crystal Structures, T. J. Wieting and M. Schlüter eds., Reidel, Dordrecht, 1979, pp. 59, 145.
3. W. Cochran, Phys. Rev. Lett. 3,412 (1959); Adv. Phys. 9, 387 (1960).
4. A typical example of the effect of Fermi surface nesting is the Peierls instability in one- dimensional metals: see R. F. Peierls, Quantum Theory of Solids, Clarendon Press, Oxford, 1955, Chap. 5.
5. C. M. Varma and W. Weber, Phys. Rev. Lett. 39, 1094 (1977).