Oscillation of higher-order neutral-type periodic differential equations with distributed arguments

We derive oscillation criteria for general-type neutral differential equations [x(t)+αx(t- τ) +βx( t+τ) ] (n) =δ ∫ab x( t-s) ds q1 ( t,s)+δ ∫cd x( t+s)ds q2 ( t,s)=0, t0, b>a<0, d>c<0, α and β are real numbers, the functions q1 ( t,s):[ t0,∞)×[ a,b ]→ and q2 ( t,s):[ t0,∞)×[ c,d ]→ are nondecreasing in s for each fixed t, and τ is periodic and continuous with respect to t for each fixed s. In certain special cases, the results obtained generalize and improve some existing ones in the literature.