2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57853Solution of the nonlinear Klein-Gordon equation perturbed by small external force is investigated. The frequency of perturbation varies slowly and passes through a resonance. The resonance generates a solitary packets of waves. Full asymptotic description of this process is presented.21 pages, LaTeXMathematical Physics37K40; 34E10; 74J30text