[1] Rogister A 1971 Phys. Fluids 14 2733

[2] Mj\o lhus E 1976 J. Plasma Phys. 16 321

[3]Mj\o lhus E 1989 Physica Scripta 40 227

[4] Ruderman M S 2002 J. Plasma Phys. 67 271

[5]Agrawal G P 2001 Nonlinear Fiber Optics 3rd edn (New
York: Academic)

[6] Tzoar N and Jian M 1981 Phys. Rev. A 23 1266

[7] Nakat I 1991 J. Phys. Soc. Jpn. 60 3976

[8] Nakata I and Ono H and Yoida M 1993 Prog. Theor. Phys.
90 739

[9]Daniel M and Veerakumar V 2002 Phys. Lett. A 302
77

[10] Kaup D J and Newell A C 1978 Prog. Theor. Phys.
19 798

[11]Cao C W and Geng X G 1990 Nonlinear Physics,
Research Reports in Physics ed Gu C H, Li Y S and Tu G Z
(Berlin: Springer) p 66

[12] Qiao Z J 1993 J. Math. Phys. 34 3110

[13] Zeng Y B 1994 J. Phys. D 73 171

[14] Zeng Y B and Hietarinta J 1996 J. Phys. A 29 5241

[15]Zeng Y B and Ma W X 1999 J. Math. Phys. 40 6526

[16]Ji J and Zhou R G 2006 Chaos, Solitons \& Fractals
30 993

[17] Geng X G and Cao C W 1999 Phys. Lett. A 261 289

[18] Babelon O and Villet C M 1990 Phys. Lett. B 237 411