PETRINA, D. Ya. States of Infinite Equilibrium Classical Systems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 55, n. 3, p. 389–399, 2003. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3913. Acesso em: 27 apr. 2025.