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2. W.O. Eckhardt, “Offswitching of Liquid-Metal Arc Switching Device by Auxiliary Arc Liquid-Metal Starvation,” U. S. Patent No. 3,586,904(1971).
3. W.O. Eckhardt, “Offswitching of Liquid-Metal Arc Switching Device by Internal Current Diversion to an Auxiliary Electrode,” U. S. Patent No. 3, 699, 384(1972).
4. W.O. Eckhardt, “Liquid-Metal Arc Cathode With Maximized Electron/Atom Emission Ratio,” U. S. Patent No. 3, 475, 636(1969).
5. W.O. Eckhardt, “Vapor-Fed Liquid-Metal Cathode,” U. S. Patent No. 3, 538, 375(1968).