Babich, Yu. A., and T. F. Michaylova. “Approximation of Periodic Functions of Many Variables by functions of Smaller Number of Variables in Orlicz Metric Spaces”. Ukrains’kyi Matematychnyi Zhurnal 70, no. 8 (August 25, 2018): 1143-1148. Accessed March 19, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1624.