@book{19156, author = {Devreese, Jozef T. and Brosens, Fons}, title = {Electron Correlations in Solids, Molecules, and Atoms. Proceedings of a NATO Advanced Study Institute on Electron Correlations in Solids, Molecules, and Atoms, July 1981, Antwerp, Belgium.}, publisher = {Plenum Press}, year = {1983}, address = {New York} }