BAK, S.M. Existence of the time periodic solutions of system of oscillators on $2D$-lattice. Carpathian Mathematical Publications, [S. l.], v. 4, n. 2, p. 175–196, 2012. Disponível em: https://vps.pnu.edu.ua/index.php/cmp/article/view/2143. Acesso em: 22 nov. 2024.