The necessary and sufficient conditions are obtained for the existence of all possible types of Pω(Y0, λ0)-solutions of non-autonomous second and third-order ordinary differential equations that are asymptotically close to linear equations. The asymptotic representation of each possible type of Pω(Y0, λ0)-solutions has been determined, and the question of their quantity has been clarified. Consequences have also been derived from the obtained theorems for cases when the equation is a linear differential equation.