SKRYPNIK, W. I. Periodic Coulomb dynamics of two equal negative charges in the field of four equal positive fixed charges. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 10, p. 1432–1442, 2020. DOI: 10.37863/umzh.v72i10.741. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/741. Acesso em: 27 apr. 2025.