Morales and Guillermo del Conde P., J. L. “An Example of Gaussian Molecular Orbital Ab-Initio Calculations Including Configuration Interaction. The H2 Molecule”. Revista Mexicana De Física, vol. 27, no. 1, Jan. 1980, pp. 55-68, https://rmf.smf.mx/ojs/index.php/rmf/article/view/1156.