-
[1]
B. Blok, Phys. Lett., B233(1989), 359,[2] A. Alekseev, S. Shatashivilli, Commun，.Math. Phys., 133(1990), 353.[3] J. Balog, L. Dabrowski and L. Feher, Phys, Lett., B244(1990), 227.[4] J. Balog, L. Dabrowski and L. Feher, DIAS-STP-90-29.[5] J.-L. Gervais, Phys. Lett., B160(1985). 279.[6] L. D. Faddeev, Commun. Math. Phys., 132(1990), 131.