@article{00035112,
title = {Periodic solutions for third order ordinary differential equations.},
journal = {Commentationes Mathematicae Universitatis Carolinae},
volume = {32},
year = {1991},
pages = {495-499},
zbl = {0751.34015},
language = {en},
url = {http://dml.mathdoc.fr/item/00035112}
}
Nieto, Juan J. Periodic solutions for third order ordinary differential equations.. Commentationes Mathematicae Universitatis Carolinae, Tome 32 (1991) pp. 495-499. http://gdmltest.u-ga.fr/item/00035112/