SKRYPNIK, W. I. Coulomb dynamics near equilibrium of two equal negative charges in the field of fixed two equal positive charges. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 9, p. 1273–1285, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1920. Acesso em: 5 dec. 2025.