1. N. Gisin and M. Rigo, J. Phys. A28 (Math. Gen.), 7375 (1995).
2. N. Gisin, J. Phys. A14 (Math. Gen.) 2259 (1981); Physica A111, 364 (1982).
3. M. Razavy and A. Pimpale, Phys. Rep. 168, 307 (1988).
4. A.O. Caldeira and A.J. Leggett, Ann. Phys. (NY) 149, 374 (1983).
5. Ł.A. Turski, Metriplectic Dynamics of Complex Systems. in: Continuum Models and Discrete Systems, (Dijon, 1989). vol. 1 G.A. Maugin, ed. Longman, London (1990).