Existence of Three Positive Periodic Solutions of Differential Equations of Second Order

@inproceedings{Wang2009ExistenceOT,
  title={Existence of Three Positive Periodic Solutions of Differential Equations of Second Order},
  author={Nianpeng Wang},
  year={2009}
}
In this paper, by using the coincidence degree method, a sufficient condition for the existence of at least three positive periodic solutions of a class of second order differential equations is obtained under the existence of upper and lower solutions. Key-Words: Periodic solutions, upper and lower solutions, coincidence degree