[1]Conti R. Nonlinear DifferentialEquations(Translated by Huang Qichang). Beijing: Science Press, 1983
[2]Zhang Zhifen, Ding Tongren. Qualitive Theory of DifferentialEquations. Beijing:Science Press, 1985
[3]Omari P, Zanolin F. On the existence of periodic solutions of force Lién ard differential equations. Nonlinear Anal, 1987,11(2): 275-284
[4]Zhang Bo. Periodic solutions of the retarded Liénard equation. Ann Math Pura Appl, 1997, 172(4): 25-42
[5]Huang Xiankai, Chen Wending.2πperiodic solutions of Duffing equa tion with delay x¨+cx·+g(x(t-τ))=p(t).Progress in natural science,1998,8(1):118-121
[6]Huang Xiankai, Xiang Zigui.2πperiodic solutions of Duffing equati on with delay x¨+g(x(t-τ))=p(t).Chinese Science Bulletin, 1994,39(3): 201-203
[7]Gains R E, Mawhin J L. Coincidence Degree, Nonlinear Differential Equations. New York:SpringerVerlag, 1977
[8]Wei Lange. Harmonic solutions and subharmonic solutions for some Duffing equation. Advances in Mathematics, 2003, 32(1): 39-46(in Chinese)
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