WANG, Gen-Qiang; CHENG, Sui Sun. Oscillation of second order differential equation with piecewise constant argument. CUBO, A Mathematical Journal, [S. l.], v. 6, n. 3, p. 55–63, 2004. Disponível em: https://cubo.ufro.cl/index.php/cubo/article/view/1633. Acesso em: 13 oct. 2025.