“…b x = ∞, as will be pointed out in the next section. Two problems have been widely studied in literature: the existence of nonoscillatory solutions and the oscillation of all solutions, see, e.g., [1], [2], [6], [7], [14] and [5], [15], [17], [18], respectively, and references therein. More difficult problems, especially those motivated by some physical applications, deal with: (i) the existence of at least one oscillatory solution; (ii) the global monotonicity of nonoscillatory solutions x, i.e.…”