Vázquez-Montiel, S., and O. García-Liévanos. “Spherical Aberration Correction Using Aspheric Surfaces With an Analytic-Numerical Method”. Revista Mexicana De Física, vol. 59, no. 3, Jan. 2013, pp. 273-0, https://rmf.smf.mx/ojs/index.php/rmf/article/view/3996.