1. W. Losch and A. J. Monhemius,Surf. Sci. 60 (1976) 196.
2. J. D. Sullivan, Technical Paper, US Bureau of Mines, No. 486 (1931).
3. V. V. Stender and A. Sultevskaya,Izv. Akad. Nauk. Kaz. SSR Ser. Khim. 101 (1951) 90.
4. T. Uchida, H. Matsumoto, S. Omori and A. Murayama,Hakko Kyokaishi 25 (1967) 168.
5. G. A. Kopylov and A. I. Orlov,Izv. Vysslzikh Uchobn. Zavedenii Tsvetn. Metall. 6 (1963) 68.