A convexity in R^2 with river metric. Gulf Journal of Mathematics, [S. l.], v. 15, n. 2, p. 25–39, 2023. DOI: 10.56947/gjom.v15i2.1226. Disponível em: https://gjom.org/index.php/gjom/article/view/1226. Acesso em: 9 nov. 2026.