00575naa#a2200169#i#450# EN\\bibl\122842 20260818163306.2 2686-9896 20260515b2026####ek#y0engy0150####ca RU PENDULUM NONLINEAR OSCILLATION STABILITY REGION Journal article Angarsk Federal State Funded Educational Establishment of Higher Education «Angarsk State Technical University» 2026 1 с. Journal article local Анализ. 517 Senotova Svetlana Anatol'evna angtu.editorum.ru