1. Differential-difference equations;Bellman,1963
2. The equation x′(t)=ax(t)+bx(t−τ) with “small” delay;Driver;Am. math. Mon.,1973
3. Introduction to the theory of differential equations with deviating arguments;El'sgol'ts,1966
4. Introduction to the theory and application of differential equations with deviating arguments;El'sgol'ts,1973
5. Oscillations of functional differential equations with retarded argument;Kusano;J. Diff. Eqns,1974