1. W.A. de Heer, Rev. Mod. Phys. 65, 611 (1993)
2. M. Brack, Rev. Mod. Phys. 65, 677 (1993)
3. N.W. Ashcroft, N.D. Mermin, Solid State Physics (Holt, Rinehart, and Winston, New York, 1976)
4. X. Li, H. Wu, X.B. Wang, L.S. Wang, Phys. Rev. Lett. 81, 1909 (1998)
5. C.E. Moore, in Atomic Energy Levels, Natl. Bur. Stand. (U.S.) Circ. (U.S. GPO, Washington, D.C., 1971), Vol. I