ET. AL., V. Sudha. Characterizations of Nnce-open and Nnce-closed Functions. Turkish Journal of Computer and Mathematics Education (TURCOMAT), [S. l.], v. 12, n. 15, p. 351–356, 2021. Disponível em: https://www.turcomat.org/index.php/turkbilmat/article/view/1849. Acesso em: 15 oct. 2025.