1. Levin,G., Goddard III.,W. A.: J. Am. Chem. Soc. (In press)
2. Levin, G.: Ph. D. Thesis, California Institute of Technology 1974
3. Goddard III., W. A.: Phys. Rev.151, 81 (1967)
4. Ladner, R.C., Goddard III., W. A.: J. Chem. Phys.51, 1073 (1967)
5. Ladner,R.C.: Ph. D. Thesis, California Institute of Technology 1972