With n even and
∫∞tn−1a(t)dt < ∞, necessary conditions for x(n)(t) + a(t)f(x(g(t))) = 0 to have a
bounded nonoscillatory solution are given. If n = 2, sufficient conditions are also
given. Conditions which insure that solutions of x(n)(t) + f(t,x(g(t))) = 0
are oscillatory or tend monotonically to zero are also presented in this
paper.