Kopotun, K. A., D. Leviatan, and I. A. Shevchuk. “Are the Degrees of the Best (co)convex and Unconstrained Polynomial Approximations the Same? II”. Ukrains’kyi Matematychnyi Zhurnal 62, no. 3 (March 25, 2010): 369–386. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2873.