del Castillo-Mussot, M., G. Vázquez Fonseca, and G. Cocoletzi. “Hydrodynamic Model for 2D Degenerate Free-Electron Gas for Arbitrary Frequencies”. Revista Mexicana De Física, vol. 49, no. 3, Jan. 2003, pp. 231-0, https://rmf.smf.mx/ojs/index.php/rmf/article/view/3157.