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2. H. Ranke, H. Bickmann, W. Kemmner, E. Räuchle, T. Magg, German patent publication No. DE 4136297 A1, 6 May 1993.
3. E. Räuchle, W. Petasch, F.K. Räuchle, H. Mügge, German Patent DE 19503205 C1, 2 May 1995.
4. H. Muegge, Muegge Electronic GmbH, private communication.