“…Over the past years, many new results have been obtained on the stability for solutions of ordinary and functional differential equations of higher order without and with delay. For instance, we draw the attention of the interested reader to the book by Reissig et al [10] and the papers by Abou El-Ela et al [1,2,3], Adesina et al [4], Omeike [8,9], Sadek [11], Tunç [12,13,14] and the references cited therein. As far as we know, researches that discussed the stability of solutions to vector differential equations can briefly be summarized as follows:…”