Jurakhonov О. . “О.А. Jurakhonov The Exact Values of the Upper Bounds for Approximation in the Mean of Some Classes of Ьivariate Functions Bу Triangular Fourier-Hermite Sums”. Bulletin of L.N. Gumilyov Eurasian National University. Mathematics, Computer Science, Mechanics Series, vol. 122, no. 1, Mar. 2018, pp. 70-75, https://bulmathmc.enu.kz/index.php/main/article/view/19.