Existence of Solutions of Degenerate Nonlinear Differential Operator Equations. Neliniini Kolyvannya, [S. l.], v. 4, n. 2, p. 252–263, 2001. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/169. Acesso em: 22 jan. 2026.