ERDOS, P.; PIRANIAN, G. Essential Hausdorff Cores of Sequences. The Journal of the Indian Mathematical Society, [S. l.], v. 30, n. 2, p. 93–115, 1966. DOI: 10.18311/jims/1966/16807. Disponível em: http://informaticsjournals.com/index.php/jims/article/view/16807. Acesso em: 8 may. 2024.