Radchenko, O. Ya., and S. Ya. Yanchenko. “Approximative Characteristics of the Nikol’skii – Besov Classes of Functions $S_{1, θ}^r B(\mathbb{R}^d)$”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 10 (October 25, 2019): 1405–1421. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1523.