1. High Power Microwave Sources, edited by V. L. Granatstein and I. Alexeff (Artech House, Boston, 1987), p 507.
2. S. Humphries, Jr. Charged Particle Beams (Wiley, New York, 1990), p 432; also available at http://www.fieldp.com/cpb.
3. C. K. Birdsall and W. B. Bridges, Electron Dynamics of Diode Regions (Academic, New York, 1966), p 71.
4. An Introduction to the Physics of Intense Charged Particle Beams
5. Relation between space charge limited current and power loss in open drift tubes