1. Ebert D. and Reinhardt H.: Nucl. Phys. B271 (1986) 188.
2. Vogl U., Klimt S., Lutz M., and Weise W.: Nucl. Phys. A516 (1990) 429, 469.
3. Ripka G., Jaminon M., Mendez-Galain R., and Stassart P.: Nucl. Phys. A537 (1992) 418.
4. Feynman R.P. and Hibbs A.R.: Quantum Mechanics and Path Integrals. McGraw-Hill, New York, 1965.
5. Blaizot J.P. and Ripka G.: Quantum Theory of Finite Systems. MIT Press, Cambridge (Mass.), 1986.