1. Keller J., Paper presented in the Sanibel Symposia (1973), published in Int. J. Quan. Chem.,9, 583 (1975).
2. Keller J., J. PhysiqueC3, 241 (1972); Keller J., XVIII Conf. on Magnetism and Magnetic Materials (1972), AIP Conf. Proc.,10, 514 (1973). Keller J., Computational Methods for Large Molecules and Localized states in Solids, Edited by F. Herman, A. D. Mc Lean and R. K. Nesbet, Plenum Press, 341?56 (1973). Keller J., Computers in Chemical Education and Research, Edited by E. V. Lude�a, N. Sabelli and A. C. Wahl, Plenum Press, 225?60 (1977).
3. Breskman D., and Kanofsky A., Phys. Letters,33b, 309 (1970).
4. Williams R. W., Phys. Letters,34b, 63 (1971).
5. Ramsey N. F., Phys. Rev.,78, 699 (1950).