1. Abdollal K, Orton H E, Reynolds M W, Robert B D, Kennedy R and Clayman B P 1982Annual Rept. Conf. Elec. Insul. and Dielectric Phenomena, Amherst, Mass 17–21 Oct. 1982, New York, pp. 604
2. Das-Gupta D K, Doughty K and Brocklay R S 1980J. Phys. D13 2101
3. Hossain M M 1988Indian J. Phys. A62 944
4. Hossain M M 1989Indian J. Phys. A63 793
5. Hossain M M 1990Pramana — J. Phys. 34 565