1. Neutronenrohre Ohne Pumpvorrichtung," Physica, vol. k, 1937;
2. pp. 1190-1199. (In German.)
3. Feb. 1959; PP- 110-111. ELECTROSTATIC PROPULSION CATHODE
4. Fig* 1. Penning Discharge Electrode Configuration Fig* 2. Plasma Source Electrode Assembly ELECTROSTATIC PROPULSION