Department of Mathematics, University of West Bohemia, Univerzitní 22, 306 14 Plzeň, Czech Republic
Copyright © 2010 Petr Tomiczek. This is an open access article distributed under the
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We prove the existence of a solution to the periodic nonlinear second-order ordinary differential equation with damping , , . We suppose that , the nonlinearity satisfies the potential Landesman Lazer condition and prove that a critical point of a corresponding energy functional is a solution to this problem.