Filobello-Nino, U., et al. “A High Accurate Approximation for a Galactic Newtonian Nonlinear Model Validated by Employing Observational Data”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 27, no. 1, Jan. 2017, pp. 139-50, https://asrjetsjournal.org/American_Scientific_Journal/article/view/1326.