1. G. Grim, Plasma Spectroscopy [in Russian], Moscow (1969).
2. W. Wiese, Diagnostics of Plasma [Russian translation], Mir, Moscow (1967).
3. A. M. Bonch-Bruevich and V. A. Khodovoi, Usp. Fiz. Nauk,93, 71 (1967).
4. L. Schott, Z. Phys.,183, 251 (1965);189, 449 (1966);206, 309 (1967).
5. R. Gebauer and H. Selhofer, Acta Phys. Austr.,31, Nos. 1?2 (1967).