1. An extensive historical review is given by H. O. Pritchard and H. A. Skinner, Chem. Rev. 55, 745 (1955); CHREAY0009-2665
2. a more recent summary and additional references are given by J. E. Huheey, Inorganic Chemistry (Harper and Row, New York, 1978).
3. R. G. Parr, R. A. Donnelly, M. Levy, and W. E. Palke, J. Chem. Phys. 68, 3801 (1978). JCPSA60021-9606
4. See also J. A. Alonso and L. A. Girifalco, J. Chem. Phys. 73, 1313 (1980) JCPSA60021-9606
5. N. K. Ray, L. Samuels, and R. G. Parr, J. Chem. Phys. 70, 3680 (1979).JCPSA60021-9606