1. Vibrations of a one-degree of freedom system with non-linear internal friction and relaxation;Osinski,1963
2. The vibrations of the system with non-linear friction and relaxation with slowly variable coefficients;Osinski,1968
3. Introduction to nonlinear mechanics;Krylov,1937
4. Asymptotic methods in the theory of nonlinear oscillations;Bogoliubov,1958
5. Problems on asymptotic theory of nonstationary oscillations;Mitropolskii,1964