RAO, K.; KISHORE, G.; VAN LUONG, N. A unique common coupled fixed point theorem for four maps under ψ - φ contractive condition in partial metric spaces. CUBO, A Mathematical Journal, [S. l.], v. 14, n. 3, p. 115–127, 2012. DOI: 10.4067/S0719-06462012000300008. Disponível em: https://cubo.ufro.cl/ojs/index.php/cubo/article/view/1335. Acesso em: 10 may. 2024.