BEG, I. Inequalities in metric spaces with applications. Topological Methods in Nonlinear Analysis, [S. l.], v. 17, n. 1, p. 183–190, 2001. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2001.012. Acesso em: 19 apr. 2024.