1. M. Rose, Relativistic Electron Theory (Wiley, New York, 1961).
2. J. D. Jackson, Classical Electrodynamics, 2nd ed. (Wiley, New York, 1975).
3. J. Slater, Quantum Theory of Atomic Structure, vol. II (McGraw-Hill, New York, 1960).
4. J. Gay, in Ultrathin Magnetic Films, ed. J. A. C. Bland and B. Heinrich (Springer Verlag, Berlin,1994).
5. H. Hohenberg and W. Kohn, Phys. Rev. 136, B864 (1964).