A Degenerate Elliptic Equation for Second Order Controllability of Nonlinear Systems. Minimax Theory and its Applications, [S. l.], v. 5, n. 2, p. 413–437, 2020. Disponível em: https://journalmta.com/index.php/jmta/article/view/97. Acesso em: 13 jun. 2026.