1. V. I. Radchenko, Zh. Éksp. Teor. Fiz. 105, 834 (1994).
2. V. I. Radchenko, Doctoral Dissertation in Mathematical Physics (Yekaterinburg, 1996).
3. M. Inokuti, Rev. Mod. Phys. 43, 297 (1971).
4. E. Clementi and C. Roetti, At. Data Nucl. Data Tables 14, 177 (1974).
5. A. A. Radtsig and B. M. Smirnov, Parameters of Atoms and Atomic Ions: A Reference Book (Énergoatomisdat, Moscow, 1986).