Positive periodic solutions to a second-order singular differential equation with indefinite weights (Q2123157)

The authors study the existence of positive periodic solutions for an equation of the type \[ x''+a(t)x=\frac{h(t)}{x^\rho}+e(t). \] The functions \(a(t)\), \(h(t)\) and \(e(t)\) are allowed to change signs. The proofs rely on the Krasnoselskii's-Guo fixed point theorem. These results are applicable both to weak and strong singularities.