[1] T. Yoneyama and J. Segie, On the stability region of scalar of delay-differential equations, J. Math. Anal. Appl., 134, 3 (1988), 408～425.
[2] J. Hale, Theory of Functional Differential Equations, Applied Mathematical Sciences 3,Springer-Verlag, New York (1977).
[3] R. Bellman and K. L. Cooke, Differential-Difference Equations,Academic Press, New York (1963).
[4] N. D. Hayes, Roots of the transcendental equation-associated with a certain difference-differential equation. J. London Math. Soc., 25, 2 (1950), 226～232.
[5] V. B. Kolmovskii and V. R. Nosov, Stabilily of Functional Differential Equations,Academic Press, London, New York (1986).
[6] T. A. Burton, A. Casal and A. Somolions, Upper and lower bounds for Liapunov functionals, Funkeal.Ekvac., 32, 1 (1989), 23～55.
[7] I. Gyori, Global attractivity in a perturbed linear delay differential equation, Applicable Analysis,34, 2 (1989), 167～181.
[8] T. Hara, T. Yonerama and R. Miyazaki, Some relines of Razunlikhins method and their applications, Funkeialaj Ekvacioj, 35, 2 (1992), 279～305.
[9] K. Kobayashi,Stability theorems for functional differential equations,Nonlinear Analysis TMA, 20, 10 (1993), 1183～1192.
[10] Liu Kaiyu, Global attractivity and uniform stability of nonautonomous delay perturbed differential equations, Hunan University Thesis (1996). (in Chinese).
[11] V. B. Kolmanovskii, L. Torell and R. Verniglio, Stability of some test equations with delay, SLAM J. Math. Anal., 25, 3 (1994), 948～961.