@article{120230, author = {Vladim\'\i r Vl\v cek}, title = {To existence of the periodic solution of a third-order nonlinear differential equation}, journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica}, volume = {29}, year = {1990}, pages = {123-163}, zbl = {0754.34037}, mrnumber = {1144836}, language = {en}, url = {http://dml.mathdoc.fr/item/120230} }
Vlček, Vladimír. To existence of the periodic solution of a third-order nonlinear differential equation. Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica, Tome 29 (1990) pp. 123-163. http://gdmltest.u-ga.fr/item/120230/
Periodic solutions to a non-linear parametric differential equatioп of the third order, Accad. Naz. Lincei, Cl.fis.mat.nat., S.VIII, vol. LXXVII, fasc.3-4, 81-86.
Inequalities, Cambridge Univ.Press, Cambridge, 1952. (1952) | MR 0046395 | Zbl 0047.05302