Джумабаева, А.А., and А.Е. Жетписбаева. 2021. “THE ORDER OF THE BEST APPROXIMATION OF FUNCTIONS IN LEBESQUE SPACE”. Bulletin of Abai KazNPU. Series of Physical and Mathematical Sciences 69 (1). Алматы, Казахстан:43-51. https://doi.org/10.51889/2020-1.1728-7901.07.