Dzyubenko, H. A., V. V. Listopad, and I. A. Shevchuk. 1993. “Uniform Estimates for Monotonic Polynomial Approximation”. Ukrains’kyi Matematychnyi Zhurnal 45 (1): 38–43. https://umj.imath.kiev.ua/index.php/umj/article/view/5780.