Necessary and sufficient conditions for existence of an “isolated” solution of a nonlinear two-point boundary-value problem. Neliniini Kolyvannya, [S. l.], v. 15, n. 4, p. 435–446, 2012. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/664. Acesso em: 21 jan. 2026.