@article{Skrypnik_2016, title={Coulomb dynamics near equilibrium of two equal negative charges in the field
of fixed two equal positive charges}, volume={68}, url={http://umj.imath.kiev.ua/index.php/umj/article/view/1920}, abstractNote={Periodic and quasiperiodic solutions of the Coulomb equation of motion of two equal negative charges in the field of two
fixed and equal positive charges are found with the help of the Lyapunov center theorem.}, number={9}, journal={Ukrainsâ€™kyi Matematychnyi Zhurnal}, author={SkrypnikW. I.}, year={2016}, month={Sep.}, pages={1273-1285} }