In this paper, we investigate the first-order neutral differential equation of Euler form with variable unbounded delay (*)frac(d, d t) fenced(x (t) - cx (αt)) + frac(1, t) underover(∑, i = 1, n) pi x (βi t) = 0, t ≥t0 >0,where 0 &le c <1, 0 <α<1, 0 <βi <1 and pi >0 are constants, i = 1, 2, ..., n . Some necessary and sufficient as well as explicit sufficient conditions for the oscillation of all solutions are established. Several relevant results in the literature are improved. ©2007 Elsevier Inc. All r...
