Riquer, V. and Ruiz-Altaba, M. (2000) “Variational spectrum of the relativistic Coulomb problem in a non-orthogonal basis”, Revista Mexicana de Física, 46(1), pp. 24–28. Available at: https://rmf.smf.mx/ojs/index.php/rmf/article/view/2922 (Accessed: 5 July 2024).