Ысмагул R.S., and Б.О. Жумартова. 2021. “CHARACTERISTIC FUNCTION OF THE SYSTEM D–EQUATIO”. Bulletin of Abai KazNPU. Series of Physical and Mathematical Sciences 75 (3). Алматы, Казахстан:29-34. https://doi.org/10.51889/2021-3.1728-7901.03.