1. Das, J.N.: International symposium on supernova and high energy astrophysics (Calcutta, Dec. 27?29); Abstract of papers, p 19 (1989)
2. Das, J.N.: Phys. Rev. A42 1376 (1990)
3. Das, J.N., Bhattacharyya, P.K.: J. Phys. B23, L 145 (1990)
4. Weigold, E., Noble, C.J., Hood, S.T., Fuss, I.: J. Phys. B12, 291 (1979)
5. McCarthy, I.E., Weigold, E., Zhang, X., Zheng, Y.; J. Phys. B22, 931 (1989)