Oscillation of second order self-conjugate differential equation with impulses

In this paper, we investigate the oscillation of second-order self-conjugate differential equation with impulsesequation(1)(a(t)(x(t)+p(t)x(t-τ))′)′+q(t)x(t-σ)=0,t≠tk,t⩾t0,equation(2)x(tk+)=(1+bk)x(tk),k=1,2,…,equation(3)x′(tk+)=(1+bk)x′(tk),k=1,2,…,where a,p,qa,p,q are continuous functions in [t0,+∞)[t0,+∞), q(t)⩾0q(t)⩾0, a(t)>0a(t)>0, ∫t0∞(1/a(s))ds=∞, τ>0τ>0, σ>0σ>0, bk>-1,bk>-1,0