Sims, J.
(2020),
Hylleraas-configuration-interaction non-relativistic energies for the 3 singlet S, 4 singlet S, 5 singlet S, 6 singlet S, and 7 singlet S excited states of the beryllium atom, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.125.006
(Accessed November 8, 2024)