Babenko, V. F., and N. V. Parfinovych. “On the Order of Relative Approximation of Classes of Differentiable Periodic Functions by Splines”. Ukrains’kyi Matematychnyi Zhurnal 62, no. 2 (February 25, 2010): 147–157. Accessed April 7, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2851.