1. Stability Theory of Differential Equations;Bellman,1953
2. Differential-Difference Equations;Bellman,1963
3. The asymptotic behavior of a class of nonlinear differential equations;Cohen,1967
4. On nonlinear oscillations for a second-order delay equations;Gollwitzer;J. Math. Anal. Appl.,1969
5. Functional Differential Equations;Hale,1968