Bounded oscillation of higher order neutral differential equations with oscillating coefficients. Zein, Ali; Abu-Kaff, Taha — 2006 Applied Mathematics E-Notes [electronic only]
On Oscillation and Nonoscillation Behaviour of Bounded Solutions of N-th Order Delay Differential Equations. Taha M. Abu-Kaff; Rajbir S. Ahiya — 1990 Forum mathematicum