GUPTA, Vijay; NOWAK, G. The rate of pointwise approximation of positive linear operators based on q-integer. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 3, p. 350–360, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2721. Acesso em: 5 dec. 2025.