Oscillation theorems for th-order neutral functional differential equations

In this paper, we consider the oscillation of n th-order neutral functional differential equations of mixed type with continuous delay of the form [ x ( t ) + λ a x ( t − τ ) + μ b x ( t + τ ) ] ( n ) + δ ( ∫ c d q ( t , ξ ) x ( t − ξ ) d ξ + ∫ c d p ( t , ξ ) x ( t + ξ ) d ξ ) = 0 , where δ = ± 1 , λ = ± 1 , μ = ± 1 , and p , q are continuous and periodic functions for t .