1. R.C. Davidson, Physics of Nonneutral Plasma, Addison-Wesley, Redwood City, CA, 1990, Chap. 2.
2. Cold Kilo-Electron Ball as Probe for Charge-Proportional Cyclotron Frequency Shift in Penning Trap Cavity
3. K.R. Spangenberg, Vacuum Tubes, McGraw-Hill, New York, 1948, Chaps. 5 and 13.
4. P. Grivet, Electron Optics, Pergamon, Oxford, 1965, Chaps. 2 and 4.
5. C. Evans, Charles Evans and Associates, Sunnyvale, CA, personal communication.