Zhelnov, O. D. “Whitney Interpolation Constants Bounded by 2 for K = 5, 6, 7”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 4 (April 25, 2003): 546–549. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/3928.