1. For a recent review on VB theory, see the special issues of J Mol Struct (THEOCHEM), (1991) 229; (1992) 259; (1992) 260; (1992) 261
2. Coulson CA (1961) Valence. Oxford University Press, London
3. Pauling L (1960) The Nature of the Chemical Bond. Cornell University Press, Ithaca, NY
4. Cooper DL, Gerratt J, Raimondi D (1991) Chem Rev 91:929
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