JOURNAL OF INEQUALITIES AND APPLICATIONS, 2007 (SCI-Expanded)
We derive oscillation criteria for general-type neutral differential equations [x(t)+alpha x(t-tau)+beta x( t+tau)]((n)) = delta integral(b)(a)x(t-s)d(s)q(1)(t, s) + delta integral(d)(c)x(t+s)d(s)q(2)(t, s) = 0, t >= t(0), where t(0) >= 0, delta = +/- 1, tau > 0, b > a >= 0, d > c >= 0, a and beta are real numbers, the functions q(1)( t, s) : [t(0), infinity) x [a, b] -> R and q(2)(t, s) : [t(0), infinity) x [c, d] -> R are nondecreasing in s for each fixed t, and t 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.