“…Such equations are frequently encountered as mathematical models of most dynamical processes in mechanics, control theory, physics, chemistry, biology, medicine, economics, atomic energy, information theory, etc. Especially, since 1960s, many good books and papers have been published and are still being published on the delay differential equations (see, for example, Burton [1,2], Burton and Zhang [3], Èl'sgol'ts [4], Èl'sgol'ts and Norkin [5], Gopalsamy [6], Hale [7], Hale and Verduyn Lunel [8], Kolmanovskii and Myshkis [9], Kolmanovskii and Nosov [10], Krasovskii [11], Sadek [15], Sinha [16], Tejumola and Tchegnani [17], Tunç [19,20,[22][23][24][25], Yoshizawa [26], Zhu [27] and the references thereof). It is also worth mentioning that the use of the Lyapunov direct method [12] for equations with delays encountered some principal difficulties.…”