SemenyukV. B. “Approximation of Differentiable Functions by Polynomial Splines in Domains With External Peaks”. Ukrains’kyi Matematychnyi Zhurnal 46, no. 9 (September 25, 1994): 1224–1233. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5639.