KALYBAY, A.A.; BAIARYSTANOV, A.O. Differential inequality and non-oscillation of fourth order differential equation. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 104, n. 4, p. 103–109, 2021. DOI: 10.31489/2021m4/103-109. Disponível em: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/478. Acesso em: 3 jul. 2025.