Oscillation theorems for nnth-order neutral functional differential equations

In this paper, we consider the oscillation of nnth-order neutral functional differential equations of mixed type with continuous delay of the form [x(t)+λax(t−τ)+μbx(t+τ)](n)+δ(∫cdq(t,ξ)x(t−ξ)dξ+∫cdp(t,ξ)x(t+ξ)dξ)=0, where δ=±1δ=±1, λ=±1λ=±1, μ=±1μ=±1, and pp, qq are continuous and periodic functions for tt.