1. Abou-El-Ela, A.M.A.: Boundedness of the solutions of certain third-order vector differential equations. Ann. Differ. Equ. 1(2), 127–139 (1985)
2. Abou-El-Ela, A.M.A., Sadek, A.I., Mahmoud, A.M., Taie, R.O.A.: A stability result for the solutions of a certain system of fourth-order delay differential equation. Int. J. Differ. Equ. 2015, Article ID 618359 (2015)
3. Afuwape, A.U.: Ultimate boundedness results for a certain system of third-order nonlinear differential equations. J. Math. Anal. Appl. 97, 140–150 (1983)
4. Afuwape, A.U., Omeike, M.O.: Further ultimate boundedness of solutions of some system of third-order nonlinear ordinary differential equations. Acta Univ. Palacki. Olomuc., Fac. rer. nat. Math. 43, 7–20 (2004)
5. Burton, T.A.: Stability and Periodic Solutions of Ordinary and Functional Differential Equations. Academic Press, Orlando (1985)