JADDOA, Aqeel F. Energy Methods For Initial –Boundary String Problem. Ibn AL-Haitham Journal For Pure and Applied Sciences, Baghdad, Iraq., v. 27, n. 2, p. 220–228, 2017. Disponível em: https://jih.uobaghdad.edu.iq/index.php/j/article/view/346. Acesso em: 26 mar. 2025.