, . . English summaries. Butlletí de la Societat Catalana de Matemàtiques, [S. l.], v. 23, n. 1, p. 173–175, 2008. Disponível em: https://revistes.iec.cat/index.php/BSCM/article/view/40231.001. Acesso em: 4 may. 2024.