The alternating lyapunov functions and preservation of invariant tori under perturbations
English version (Springer): Ukrainian Mathematical Journal 39 (1987), no. 1, pp 36-42.
Citation Example: Kulik V. L. The alternating lyapunov functions and preservation of invariant tori under perturbations // Ukr. Mat. Zh. - 1987. - 39, № 1. - pp. 45–52.
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