1.
BERGER, Melvyn S. and ZHANG, Luping. New method for large quasiperiodic nonlinear oscillations with fixed frequencies for the nondissipative second type Duffing equation. Topological Methods in Nonlinear Analysis. Online. 1 December 1995. Vol. 6, no. 2, pp. 283 - 293. [Accessed 22 July 2024].