(1) K. Siegbahn, C. Nordling, A. Fahlman, R. Nordberg, K.Hamrin, J.Hedman, G. Johansson, T. Bergmark, S.E.Karlsson, I. Lindgren and B. Lindberg: ESCA-Atomic, Molecular and Solid State Structure by Means of Electron Spectroscopy, Nova Acta Reg. Soc. Sci. Uppsaliensis, Ser. IV, 20 (1967).