[1] Luo Guojun. Anote stochastic power problem about weak connection line[J]. Technologyof Electrical Network,1984,(3-4):12～21.(in Chinese)
[2] Wang Lian. Anonlinear O D Ex + R F′(x)⒒x + 1 L F(x) = Acosωt, F(x) = αx + βx³ from projectof high tension powertransmission[J]. Mathematicsin Practice and Theory,1978,(1):50～58.(in Chinese)
[3] Qin Yuanxun,etal. Stability Theory and Applications[M]. Beijing: Science Press,1990.(in Chinese)
[4] Yoshizawa. Stability Theory and Existence of Periodic Solutions and Almost Periodic Solutions[M]. Translated by Zheng Zuxiu. Nanning: Guangxi People’s Publishing House,1985,167～175.(Chinese version)
[5] Langenhop C E, Seifert G. Almostperiodic solutions ofsecond ordernonlinear differentialequations with almostperiodic forcing[J]. Proc Amer Math Soc,1959,10:425～432.