1. Stability and Asymptotic Behavior of Differential-Delay Equations;Grossman,1969
2. Asymptotic stability for one-dimensional differential-delay equations;Yorke;J. Differential Equations,1970
3. S. E. Grossman and J. A. Yorke, Asymptotic behavior and stability criteria for differential delay equations, to appear.
4. Stability theory by Liapunov's second method;Yoshizawa;J. Math. Soc. Japan,1966
5. Differential-Difference Equations;Bellman,1963