TIGAN, Gheorghe. ON A THREE-DIMENSIONAL NONLINEAR DIFFERENTIAL SYSTEM. Matematichki Bilten, [S. l.], v. 30, n. 1, p. 9–16, 2006. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1720. Acesso em: 14 aug. 2026.