Lasuriya, R.A. and Stepanets, O.I. (2007) “Multiple Fourier sums and ψ-strong means of their deviations on the classes of ψ-differentiable functions of many variables”,
Ukrains’kyi Matematychnyi Zhurnal, 59(8), pp. 1075–1093. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/3371 (Accessed: 10 April 2025).