1.
Serdyuk AS, Stepanets OI. Lower bounds for widths of classes of convolutions of periodic functions in the metrics of $C$ and $L$. Ukr. Mat. Zhurn. [Internet]. 1995Aug.25 [cited 2024Nov.24];47(8):1112-21. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5507