Jafarov, S. Z. “Linear Methods for Summing Fourier Series and Approximation in Weighted Lebesgue Spaces With Variable Exponents”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 66, no. 10, Oct. 2014, pp. 1348–1356, https://umj.imath.kiev.ua/index.php/umj/article/view/2226.