GAMAR, I. H.; BASHIR, M. A. Invariant Variational Problems. American Scientific Research Journal for Engineering, Technology, and Sciences, Jordan, v. 61, n. 1, p. 268–279, 2019. Disponível em: https://asrjetsjournal.org/American_Scientific_Journal/article/view/5305. Acesso em: 18 sep. 2025.