1. \bibitem{1} T. A. Ademola, P. O. Arawomo, Asymptotic behaviour of solutions of third order nonlinear differential equations, \emph{Acta Univ. Sapientiae Math.} \textbf{3} (2011), 197--211.
2. \bibitem{2} T. A. Burton, \textit{Stability and Periodic Solutions of Ordinary and Functional Differential Equations, Mathematics in Science and Engineering Vol. 178}, Academic Press, Orlando, 1985.
3. \bibitem{3} L. \`{E}. \`{E}l'sgol'ts, \textit{Introduction to the theory of differential equations with deviating arguments}, Translated from the Russian by Robert J. McLaughlin Holden-Day, Inc., San Francisco, Calif.-London-Amsterdam, 1966.
4. \bibitem{4} L. \`{E}. \`{E}l'sgol'ts, S. B. Norkin, \textit{Introduction to the theory and application of differential equations with deviating arguments}, Translated from the Russian by John L. Casti. Mathematics in Science and Engineering, Vol. 105. Academic Press [A Subsidiary of Harcourt Brace Jovanovich, Publishers], New York-London, 1973.
5. \bibitem{5} J. O. C. Ezeilo, On the stability of solutions of certain differential equations of the third order, \emph{Quart. J. Math. Oxford Ser. } \textbf{11}(2) (1960), 64-69.