YURYK, I. I. Nonlinear d’alembert equation in the pseudo-euclidean space $R_{2,n}$ and its solutions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 6, p. 820–827, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4476. Acesso em: 27 apr. 2025.