H.  Pathak, Sahoo, B. K., Sengupta, T., Das, B. P., Vaval, N., and Pal, S., ?Relativistic equation-of-motion coupled-cluster investigation of the trends of single and double ionization potentials in the He and Be isoelectronic systems?, Journal of Physics B-Atomic Molecular and Optical Physics, vol. 48, no. 11, p. 115009, 2015.