YEHORCHENKO , I. A.; VOROBYOVA, A. I. Conditional and hidden infinite-dimensional symmetries of wave equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 74, n. 3, p. 335–341, 2022. DOI: 10.37863/umzh.v74i3.7035. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7035. Acesso em: 7 apr. 2025.