ABSTRACT
This chapter investigates the neutral differential equations of odd order and of even order separately. It presents some comparison results for oscillation of odd order equations. The chapter also presents some criteria for oscillation and for the existence of positive solutions of odd order equations. It obtains some oscillation results for even order equations. The chapter deals with the classification of nonoscillatory solutions of higher order equations, and provides the existence results for solutions of various asymptotic behavior. It is concerned with the existence of oscillatory solutions of higher order equations. The chapter describes the oscillation and nonoscillation of equations with nonlinear neutral terms. It also investigates the behavior of solutions of even order neutral differential equations of unstable type. The chapter considers the existence of positive solutions of higher order neutral delay differential equations of the unstable type.
