Sako, T., Paldus, J., Ichimura, A., & Diercksen, G. H. F. (2012). Origin of the first Hund rule and the structure of Fermi holes in two-dimensional He-like atoms and two-electron quantum dots. Journal of Physics B: Atomic, Molecular and Optical Physics, 45(23):, pp. 1-13. doi:10.1088/0953-4075/45/23/235001.