R. VEMBU; A. BOWRNA. A generalization of natural density. Malaya Journal of Matematik, India, v. 4, n. 03, p. 388–391, 2016. DOI: 10.26637/mjm403/006. Disponível em: https://www.malayajournal.org/index.php/mjm/article/view/547. Acesso em: 5 nov. 2024.