Triple positive solutions for a class of two-point boundary-value problems. A fundamental approach . Neliniini Kolyvannya, [S. l.], v. 15, n. 2, p. 233–243, 2012. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/648. Acesso em: 21 jan. 2026.