Jetpisbayeva A, Jumabayeva A. Upper Estimates of the angle best approximations of generalized Liouville-Weyl derivatives. M [Internet]. 2021 Sep. 30 [cited 2025 Jul. 4];103(3):54-67. Available from: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/457