GURDAL, M.; SAVAŞ, E. $A$-cluster points via ideals. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 69, n. 3, p. 324–331, 2017. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1699. Acesso em: 5 dec. 2025.