SkrypnikW. I. (2016) “Coulomb dynamics near equilibrium of two equal negative charges in the field of fixed two equal positive charges”, Ukrains’kyi Matematychnyi Zhurnal, 68(9), pp. 1273-1285. Available at: http://umj.imath.kiev.ua/index.php/umj/article/view/1920 (Accessed: 29November2020).