MATEHKOLAEE, Mahmood Jaafari. Positive Solutions for a Class of Semipositone Problems. MATEMATIKA, [S. l.], v. 28, p. 49–52, 2012. DOI: 10.11113/matematika.v28.n.314. Disponível em: https://matematika.utm.my/index.php/matematika/article/view/314. Acesso em: 7 may. 2024.