Kalchuk, I.V. (2007) “Approximation of ( ψ, β )-differentiable functions defined on the real axis by Weierstrass operators”,
Ukrains’kyi Matematychnyi Zhurnal, 59(9), pp. 1201–1220. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/3382 (Accessed: 16 April 2025).