1. I. Silisteanu, Rom. J. Phys. 41 (1996) 43.
2. M. Mirea, Ch. 19 in Heavy Elements and Related New Phenomena, Vol. II (World Scientific, Singapore, 1999) 765.
3. G. Stratan, Internat. J. Mod. Phys. E 10 (2001) 367.