1. S. W. Barwick, Ph. D. Thesis, Univ. of California, Berkeley, 1986, chapter 3.
2.  idem chapter 4.
3. I. Silisteanu, Nucl. Phys. A 485 (1988) 93.
4. I. V. Poplavsky, Izv. AN SSSR, Ser. Fiz. 53 (1989) 85.