Ospanov К. . and Moldagali Е. . (2025) “CORRECTNESS CONDITIONS FOR FOURTH ORDER DIFFERENTIAL EQUATIONS WITH VARIABLE COEFFICIENTS”, Bulletin of Abai KazNPU. Series of Physical and Mathematical sciences. Almaty, Kazakhstan, 90(2), pp. 116–123. doi: 10.51889/2959-5894.2025.90.2.010.