Babenko, V. F., & Parfinovych, N. V. (2009). Nonsymmetric approximations of classes of periodic functions by splines of defect 2 and Jackson-type inequalities. Ukrains’kyi Matematychnyi Zhurnal, 61(11), 1443-1454. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/3113