Suleimenov Ж. and Kuanysh С. 2020. ON THE EXISTENCE OF A CONDITIONALLY PERIODIC SOLUTION OF A QUASILINEAR SYSTEM DIFFERENTIAL EQUATION IN THE CRITICAL CASE . Bulletin of Abai KazNPU. Series of Physical and mathematical sciences. 72, 4 (Dec. 2020), 56–62. DOI:https://doi.org/10.51889/2020-4.1728-7901.08.