GoncharovS. V., MotornyiV. P., and NitiemaP. K. 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.