Necessary and sufficient conditions for the existence of solutions of nonlinear nonautonomous periodic problem for Hills equation in the case of parametric resonance. A characteristic feature of the task is the need of finding. as desired solution. and the corresponding eigenfunction. https://www.spidertattooz.com/2ft-LED-Strip-Light-Fixture-10-19-Watts-3000-Lumens-35K-40K-50K-120-277V/