Stepanets, O. I. (2001) “Approximation Characteristics of the Spaces $S_p^{ϕ}$ in Different Metrics”, Ukrains’kyi Matematychnyi Zhurnal, 53(8), pp. 1121-1146. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4331 (Accessed: 26May2024).