1. U. Gelius: J. Electron Spectrosc.5, 985 (1974)
2. W.C. Price, A.W. Potts, D.G. Streets: In Electron Spectroscopy, ed, by D.A. Shirley (North-Holland, Amsterdam 1972 ) p. 187
3. K. Siegbahn: In Electron Spectroscopy, ed. by D.A. Shirley (North-Holland, Amsterdam 1972) p.15; K. Siegbahn: J. Electron Spectrosc.5, 3 (1974)
4. D.W. Turner, C. Baker, A.D. Baker, C.R. Brundle: Molecular Photoelectron Spectroscopy ( Wiley, London 1970 )
5. H. Fellner-Feldegg: Wiss. Z. Karl-Marx-Univ. Leipzig, Math-Naturwiss. R.25, 355 (1976)