1. M. Anderegg, Rapport de thèse, EPUL (1968).
2. L. A. Pétermann,Comparison between a Quadrupole Mass Filter and an Omegatron, Leybold Heraeus Symposium (1968).
3. S. Garbe, Adv. Vacuum Sci. Techn.1, 404 (1960).
4. A. Klopfer, W. Schmidt, Vacuum10, 363 (1960).
5. P. Genequand, Surface Science25, 643 (1971).