GogoladzeL., and TsagareishviliV. 2017. “Convergence of Fourier Series of Functions $\text{Lip} 1$ With respect to General Orthonormal Systems”. Ukrains’kyi Matematychnyi Zhurnal 69 (4), 466-77. http://umj.imath.kiev.ua/index.php/umj/article/view/1710.