The Radial Expectation Values for Ground Neutral Atom (Z=2-54)
Zheng Neng-Wu, Sun Yu-Jie, Su Wei, Zeng Rong, Zhang Yi
Acta Phys. -Chim. Sin. . 1999, (05): 443 -448 .  DOI: 10.3866/PKU.WHXB19990511