1. V. F. Kiselev, Yu. A. Zarif'yants, and S. N. Kozlov, Problems of the Physical Chemistry of the Surface of Semiconductors [in Russian], Nauka, Novosibirsk (1978).
2. A. M. Mirtazin and Yu. A. Zarif'yants, Fiz. Tekh. Poluprovodn.,7, 2041 (1973).
3. H. J. Van Hove, Surf. Sci.,22, 85 (1970).
4. O. V. Snitko, Ukr. Fiz, Zh.,2, 68 (1957).
5. I. A. Karpovich, B. N. Zvonkov, and M. A. Rizakhanov, Fiz. Tverd. Tela (Leningrad),8, 2220 (1970).