KalchukI. V. “Approximation of ( ψ, β )-Differentiable Functions Defined on the Real Axis by Weierstrass Operators”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 9 (September 25, 2007): 1201–1220. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3382.