1. Filippov A.T., Isaev A.P., Kurdikov A.B., Mod. Phys. Lett.A7 (1992), 2129.
2. Zamolodchikov A.B., Fateev V.A., Sov. Phys. JETP62 (1985), 215; Pasquer V., Saleur H., Nucl. Phys.B330 (1990), 523.
3. Greenberg O., Phys. Rev.D43 (1991), 4111; Aneziris C., Balachandran A.P., Sen D., Int. J. Mod. Phys.A6 (1991), 4721; Forte S., Rev. Mod. Phys.64 (1992), 193.
4. Polychronakos A.P., Mod. Phys. Lett.A5 (1990), 2325; Floreanini R., Vinet L., J. Phys.A23 (1990), L1019.
5. Faddeev L.D., Reshetikhin N.Yu., Takhtajan L.A., Algebra i Anal.1 (1989), 178 (in Russian); English translation, Leningrad Math. J.1 (1990), 193; Manin Yu.I.Preprint CRM-1561, Montreal, 1988: Corrigan E., Fairlie D., Fletcher P., // J. Math. Phys. V. 31. 1990.