Б.А. Дуйсенгалиева, А.С. Науразбекова. An example of a non-triangulable derivation of a differential polynomial algebra of rank 2. mathmc [Internet]. 2019 Sep. 30 [cited 2024 May 18];128(3):53-7. Available from: https://bulmathmc.enu.kz/index.php/main/article/view/50