1. Abdelatif, T.E.: Ph.D. Thesis, University of Rochester (1985)
2. Ali, S., Ahmed, Z., Mirza, A.M., Ahmed, I.: Phys. Lett. A 373, 2940 (2009)
3. Aller, L.H.: Atoms, Stars and Nebulae, 3rd edn. Cambridge University Press, Cambridge (1998)
4. Ando, H., Osaki, Y.: PASJ 27, 581 (1975)
5. Antia, H.M., Basu, S.: Astrophys. J. 644, 1292 (2006)