1. A.B. Fowler, F.F. Fang, W.E. Howard and P.J. Stiles, in: Proc. Intern. Conf. on the Physics of Semiconductors, Kyoto; J. Phys. Soc. Japan Suppl. 21 (1966) p. 331.
2. See Y. Uemura, in: Proc. 2nd Intern. Conf. on Solid Surfaces, Kyoto; Japan. J. Appl. Phys. Suppl. 2, Pt. 2 (1974) 17, and references cited there.
3. See Y. Uemura, in: Proc. Intern. Conf. on Physics of Semiconductors, Stuttgart, 1974 (Teubner, Stuttgart, 1974) p. 665, and references cited there.
4. P.J. Stiles, in: Proc. 2nd Intern. Conf. on Solid Surfaces, Kyoto; Japan. J. Appl. Phys., Suppl. 2, Pt. 2 (1974) 333.
5. T. Ando, Y. Matsumoto, Y. Uemura, M. Kobayashi and K.F. Komatsubara, J. Phys. Soc. Japan 32 (1972) 859.