“…A solution of equation (1) is said to be oscillatory if it is neither eventually positive nor eventually negative, and it is nonoscillatory otherwise. From a review of the literature, it is known that there are many results available on the oscillatory and asymptotic behavior of solutions of equation (1) when the neutral term is nonnegative, i.e., p n ≤ 0; see, for example, [1,2,3,4,6,7] and the references cited therein. However, there are very few results available on the oscillatory behavior of solutions of equation (1) when the neutral term is negative; see, for example, [1,2,5,8,9,10,11,12], and the references therein.…”