Shydlich, A. L. “On Saturation of Linear Summation Methods for Fourier Series in the Spaces $S_{\varphi} ^p$”. Ukrains’kyi Matematychnyi Zhurnal 56, no. 1 (January 25, 2004): 133–138. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/3736.