KryakinY. V. “On the Approximation by Chebyshev Splines in the Metric of $L_p, P > 0$”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 50, no. 9, Sept. 1998, pp. 1193-01, https://umj.imath.kiev.ua/index.php/umj/article/view/4835.