Oscillating and Periodic Solutions of Equations of the Type ẍ + f1(x) ẋ + f2(x) ẋ2 + g(x) = 0

In this paper we consider equations of the type ẍ + f1(x) ẋ + f2(x) ẋ2 + g(x) = 0 and study their qualitative behavior from the point of view of oscillation and periodicity of the solutions.