1. H.W. Werner: In Electron Microscopy 1980, Vol.3, Analysis, ed. by R. Brederoo and V.E. Cosslett (Published by the Seventh European Congress on Electron Microscopy Foundation, Leiden 1980) p.200
2. H.W. Werner, H.A.M. de Grefte: Vakuum-Technik 17, 37 (1968)
3. H.W. Werner: In Electron and Ion Spectroscopy of Solids, ed. by W. Dekeyser, J. Vennik, and L. Fiermans (Plenum, New York 1978) p.324
4. H. Liebl: J. Phys. E8, 797 (1975)
5. P. Gourgout: Private communication (1978)