W. J. Lauderdale, J. F. Stanton, J. Gauss, J. D. Watts, and R. J. Bartlett, “Restricted open-shell Hartree-Fock based many-body perturbation theory: Theory and application of energy and gradient calculations,” J. Chem. Phys., 97 (1992). DOI: 10.1063/1.463664
