[1] Pecora L M and Carroll T L 1990 Phys. Rev. Lett.
64 821

[2] Park J H 2005 Int. J. Nonli. Sci. Numer. Simul.
6 201

[3] Bai E W and Lonngren K E 2000 Cha. Soli. Frac.
11 1041

[4] Park J H and Kwon OM 2005 Cha. Soli. Frac.
23 445

[5] Wu X and Lu J 2003 Cha. Soli. Frac. 18 721

[6]Chen G and Dong X 1998 From Chaos to Order
(Singapore: World Scientific) chap 1 p 10

[7]Yan Z Y 2005 Phys. Lett. A 342 309

[8]Kanellakopoulos I and Kokotovic P V 1991 IEEE Trans.
Autom. Control. 36 1241

[9]Wang C and Ge S S 2001 Int. J. Bifur. Chaos Appl.
Sci. Eng. 11 1115

[10]Ren H P and Liu D 2002 Chin. Phys. Let. 19
1054

[11] Chen Y and Li X 2007 Z. Naturfor. 62a 22

[12] Hitzl DL and Zele F 1985 Physi. D 14 305

[13]Feng C F, Zhang Y and Wang Y H 2006 Chin. Phys.
Lett. 23 1418

[14]Li G H 2007 Chaos, Solitons {\rm \& Fractals
32 1786

[15]L\"u J H, Han F L, Yu X H and Chen G R 2004
Automatics 40 1677

[16]L\"u J H and Chen G R 2006 Int. J. Bifur. Chaos.
16 775