“…Table IV presents the calculated eigenvalues of some representative states with n ≤ 6 at selected values of the screening parameter (weak and strong screenings in the left and right respectively). Lower states have been examined by many methods; e.g., Rayleigh-Schrödinger perturbation expansion [21], variational methods [6,15,16], Padé approximations [20], shifted 1/N expansions [22,25], numerical calculations through direct integration of the SE [30] or by the Ritz method [31], etc. Other works include [12,33].…”