1. Ohkawa, F.J., Uemura, Y.: J. Phys. Jpn.37, 1325 (1974)
2. Takada, Y., Arai, K., Uchimura, N., Uemura, Y.: J. Phys. Soc. Jpn.49, 1851 (1980)
3. Takada, Y., Arai, K., Uemura, Y.: Proceedings of the International Conference on Physics of Narrow Gap Semiconductors, Linz 1981. In: Lecture Notes in Physics. Gornik, E., Heinrich, H., Palmetshofer, L. (eds.), Vol. 152, p. 101. Berlin, Heidelberg, New York: Springer 1982
4. Marquez, G.E., Sham, L.J.: Surf. Sci.113, 131 (1982); Marquez, G.E.: Ph.D. Thesis, San Diego 1982
5. Ando, T.: J. Phys. Soc. Jpn.54, 2676 (1985)