DoroninV. G., and LigunA. A. “Exact Constant in the Jackson Inequality in the Space <i>L</i><sub>2</Sub&gt;”. Ukrains’kyi Matematychnyi Zhurnal 46, no. 9 (September 25, 1994): 1261–1265. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5643.