Zhao, Fukun; Wu, Xian Existence and multiplicity of nonzero periodic solution with saddle point character for some nonautonomous second order systems. (English) Zbl 1079.34519 J. Math. Anal. Appl. 308, No. 2, 588-595 (2005). MSC: 34C25 58E05 PDFBibTeX XMLCite \textit{F. Zhao} and \textit{X. Wu}, J. Math. Anal. Appl. 308, No. 2, 588--595 (2005; Zbl 1079.34519) Full Text: DOI
Zhao, Fukun; Wu, Xian Existence and multiplicity of periodic solution for non-autonomous second-order systems with linear nonlinearity. (English) Zbl 1087.34022 Nonlinear Anal., Theory Methods Appl., Ser. A, Theory Methods 60, No. 2, 325-335 (2005). Reviewer: Bojidar Cheshankov (Sofia) MSC: 34C25 34B15 37J45 47J30 PDFBibTeX XMLCite \textit{F. Zhao} and \textit{X. Wu}, Nonlinear Anal., Theory Methods Appl., Ser. A, Theory Methods 60, No. 2, 325--335 (2005; Zbl 1087.34022) Full Text: DOI
Zhao, Fukun; Wu, Xian Periodic solutions for a class of nonautonomous second-order systems. (English) Zbl 1050.34062 J. Math. Anal. Appl. 296, No. 2, 422-434 (2004). Reviewer: Peter Smith (Keele) MSC: 34C25 PDFBibTeX XMLCite \textit{F. Zhao} and \textit{X. Wu}, J. Math. Anal. Appl. 296, No. 2, 422--434 (2004; Zbl 1050.34062) Full Text: DOI
Zhao, Fukun; Wu, Xian Saddle point reduction method for some non-autonomous second order systems. (English) Zbl 1053.34039 J. Math. Anal. Appl. 291, No. 2, 653-665 (2004). Reviewer: Sergei A. Brykalov (Ekaterinburg) MSC: 34C25 47J30 PDFBibTeX XMLCite \textit{F. Zhao} and \textit{X. Wu}, J. Math. Anal. Appl. 291, No. 2, 653--665 (2004; Zbl 1053.34039) Full Text: DOI