1. See, for example, P.J. Dean and D.C. Herbert: Topics in Current Physics, Vol. 14, edited by K. Cho (Springer, Berlin, 1979) p.55.
2. G. Kirczenow, Can. J. Phys. 55, 1787 (1977).
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4. H. Nakata, T. Yodo and E. Otsuka, Solid State Commun. 45, 55 (1983).
5. H. Nakata and E. Otsuka, Phys. Rev. B29, 2347 (1984).