Note on existence of periodic solutions to the third-order nonlinear differential equation.
(English).Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica,
vol. 29
(1990),
issue 1,
pp. 165-195
[1] Vlček V.: To existence of the periodic solution of a third-order nonlinear differential equation. Acta Univ. Palack. Olom., F.R.N. 1990, Math. XXIX, Tom 97 (in print). MR 1144836 | Zbl 0754.34037