1. M. Q. Tran, Phys. Scr. 20, 317 (1979).PHSTBO0031-8949
2. G. C. Das and S. G. Tagare, Plasma Phys. 17, 1025 (1975).PLPHBZ0032-1028
3. G. O. Ludwig, J. L. Ferreira, and Y. Nakamura, Phys. Rev. Lett. 52, 275 (1984).PRLTAO0031-9007
4. S. Watanabe, J. Phys. Soc. Jpn. 53, 950 (1984).JUPSAU0031-9015
5. A. D. Pataraya and G. D. Chagelishvili, Sov. J. Plasma Phys. 3, 736 (1977).SJPPDC0360-0343