PODLEVS’KYI, B. M. Variational approach to the solution of linear multiparameter eigenvalue problems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 9, p. 1247–1256, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3096. Acesso em: 11 apr. 2025.