Screening constant by unit nuclear charge calculations for (n s2)1Se, (np2)1De and (N s n p)1P° excited states of He-like systemsI. Sakho, A. S. Ndao, M. Biaye and A. WagueEur. Phys. J. D, 47 1 (2008) 37-44DOI: https://doi.org/10.1140/epjd/e2008-00018-2