“Orthoprotection Widths of Classes $L_{\beta, P}^\psi$ of Periodic Functions in the Space $L_q$”. Transactions of Institute of Mathematics, the NAS of Ukraine 12, no. 4 (June 16, 2015): 111–124. Accessed September 29, 2026. https://trim.imath.kiev.ua/index.php/trim/article/view/286.