1. A. R. Shul’man and S. A. Fridrikhov, Secondary Emission Methods of Studying Solids [in Russian], Nauka, Moscow (1977), 552 pp.
2. S. A. Komolov, Integral Secondary-Electron Surface Spectroscopy [in Russian], Leningrad State University Press, Leningrad (1986), 180 pp.
3. N. E. Christensen and R. F. Willis, J. Phys. C 12, 167 (1979).
4. I. Schäfer, M. Schlüter, and M. Skibowski, Phys. Rev. B 35, 7663 (1987).
5. J. U. Mack, E. Bertel, F. P. Netzer, and D. R. Lloyd, Z. Phys. B 63, 97 (1986).