Note on the paper of Džurina and Stavroulakis

In this paper we will establish some new oscillation criteria for the second-order retarded differential equation of the form(r(t)|u′(t)|α-1u′(t))′+p(t)|u[τ(t)]|α-1u[τ(t)]=0.The results obtained essentially improve and extend those of Džurina and Stavroulakis [Oscillation criteria for second-order delay differential equations, Appl. Math. Comput., 140 (2003) 445-453]. An open problem is proposed at the end of this paper.