Li, Yongxiang Positive periodic solutions to nonlinear second-order ordinary differential equations. (Chinese. English summary) Zbl 1018.34046 Acta Math. Sin. 45, No. 3, 481-488 (2002). Summary: The author investigates the existence of periodic solutions to nonlinear second-order ordinary differential equations \[ u''(t)+ a(t) u(t)= f(t,u(t)). \] By using Krasnoselskij’s fixed-point theorem of cone map, some existence and multiplicity results on positive periodic solutions are obtained. Cited in 19 Documents MSC: 34C25 Periodic solutions to ordinary differential equations 34B18 Positive solutions to nonlinear boundary value problems for ordinary differential equations Keywords:existence; nonlinear second-order ordinary differential equations; positive periodic solutions PDFBibTeX XMLCite \textit{Y. Li}, Acta Math. Sin. 45, No. 3, 481--488 (2002; Zbl 1018.34046)