1. See for instance S. Fantoni, in: Proceed. of the Workshop on Heavy-Quark Factory and Nuclear-Physics Facility with Superconducting Linacs, Courmayeur 1987, ed. by E. De Sanctis, M. Greco, M. Piccolo and S. Tazzari, Bologna, pag. 745 (1988) and references quoted therein.
2. See, e.g., W. M. Alberico, M. Bregola, R. Cenni and A. Molinari, Nuovo Cimento 58A (1980) 31.
3. W. M. Alberico, R. Cenni, P. De Chiara and A. Molinari, La Rivista del Nuovo Cimento, vol. 3 n. 1 (1980).
4. F. Gross and D.O. Riska, Phys. Rev. C36 (1987) 1928.
5. A.L. Fetter and J.D. Walecka, Quantum Theory of Many-Particle Systems, McGraw-Hill, New York (N. Y.) (1971).