Abstract
In this work, we study the oscillatory behavior of even-order neutral delay differential equations upsilon n(l)+b(l)u(eta(l))=0, where l >= l0, n >= 4 is an even integer and upsilon=u+a(u degrees mu). By deducing a new iterative relationship between the solution and the corresponding function, new oscillation criteria are established that improve those reported in (T. Li, Yu.V. Rogovchenko in Appl. Math. Lett. 61:35-41, 2016).