1. Asymptotic Methods in the Theory of Nonlinear Oscillations;Bogolyubov,1961
2. Stability of Solutions of Differential Equations in Banach Spaces;Daleckij,1974
3. Elements of the Theory of Multi-Frequency Oscillations;Samoilenko,1987
4. Topological Dynamics and Poisson's Stability of Solutions of Differential Equations;Scherbakov,1972
5. Poisson's Stability of Motions of Dynamical Systems and Solutions of Differential Equations;Scherbakov,1985