GAMAR, I. H. .; BASHIR, M. A. . Invariant Variational Problems. American Scientific Research Journal for Engineering, Technology, and Sciences, [S. l.], v. 61, n. 1, p. 268–279, 2019. Disponível em: https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/5305. Acesso em: 3 may. 2024.