RukasovV. I. and StepanetsO. I. (2003) “Best ‘Continuous’ $n$-Term Approximations in the Spaces $S_\phi ^p$”, Ukrains’kyi Matematychnyi Zhurnal, 55(5), pp. 663-670. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3941 (Accessed: 25November2024).