“…without logarithmic terms), the convergence of these series has been proven in [9,10]. In the general case, recent general results on singular analysis for PDEs by Kichenassamy and co-workers [11,12,13] strongly suggest that that the Psi-series are convergent in general as has been successfully demonstrated on many specific examples [14,15,16,17]. However, in the absence of a well-defined rigorous proof, we leave here the convergence of the Psi-series as an assumption.…”