1. Radom,L. and Pople,J.A.: MTP international review of science, Theoretical chemistry, Chapter 3, W. B. Brown (Ed.). London: Butterworths 1972
2. Ditchfield,R., Hehre,W.J., Pople,J.A., Radom,L.: Chem. Phys. Letters5, 13 (1970)
3. Margenau,H., Kester,N.R.: Theory of intermolecular forces, 2nd Ed. New York: Pergamon Press, 1972
4. Correlation effects in atoms and molecules. Advan. Chem. Phys.14, 1969
5. Sinanoglu,O., Bruekner,K.A.: Three approaches to electron correlation in atoms. New Haven: Yale University Press 1970