Goncharov, S. V., V. P. Motornyi, and P. K. Nitiema. 2010. “On the Mean Convergence of Fourier–Jacobi Series”. Ukrains’kyi Matematychnyi Zhurnal 62 (6), 814–828. https://umj.imath.kiev.ua/index.php/umj/article/view/2912.