KalchukI. V., and KharkevychYu. I. “Approximation of (ψ, β)-Differentiable Functions by Weierstrass Integrals”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 7 (July 25, 2007): 953–978. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3359.