Dzyubenko, G. A. “An Interpolatory Estimate for Copositive Polynomial Approximations of Continuous Functions”. Ukrains’kyi Matematychnyi Zhurnal 74, no. 4 (May 20, 2022): 496–506. Accessed April 7, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/7103.