1. G. R. Freeman, Canad. J. Chem.,44, 245 (1966).
2. A. L. Buchachenko and O. P. Tkacheva, Kinetika i kataliz,7, 777 (1966).
3. A. Trottman-Dickenson, J. Chem. Soc., A, 1621 (1966).
4. P. O. Löwdin, Rev. Mod. Phys.,34, 80 (1962).
5. Rudenberg, The Physical Nature of the Chemical Bond [Russian translation], ?Mir,? Moscow (1965).