1. Bekenstein, J. D., and Schiffer, M. (1994).Physical Review Letters,72(16), 2512.
2. Chung, Y., Hirose, H., and Suckewer, S. (1989).Physical Review A: General Physics,40(12), 7142.
3. Dirac, P. A. M. (1930).The Principles of Quantum Mechanics, Oxford University Press, Oxford.
4. Einstein, A. (1917).Physikalische Zeitschrift,XVIII, 121 [reprinted fromMitteilungen der Physikalischen Gesellschaft Z�rich (1916)].
5. Herzberg, G. (1944).Atomic Spectra and Atomic Structure, Dover, New York.