Hydrogenic impurity states in CdSe/ZnS and ZnS/CdSe core-shell nanodots with dielectric mismatch M. Cristea and E.C. Niculescu Eur. Phys. J. B, 85 6 (2012) 191 Published online: 06 June 2012 DOI: 10.1140/epjb/e2012-21051-2