1. A simple proof of a well-known oscillation theorem;Coles,1968
2. An oscillation criterion for second-order linear differential equations;Coles,1968
3. Introduction to the Theory of Differential Equations with Deviating Arguments;El'sgol'ts,1966
4. On non-linear oscillations for a second-order delay equation;Gollwitzer;J. Math. Anal. Appl.,1969
5. H. E. Gollwitzer, Non-oscillation theorems for a non-linear differential equation, to appear.