1. Electrostatic Propulsion
2. H. Mirels, inElectrostatic Propulsionedited by D. B. Langmuir, E. Stuhlinger, and J. M. Sellen (Academic Press Inc., New York, 1961), p. 373.
3. J. M. Sellen, Jr., and H. Shelton, inElectrostatic Propulsion, edited by D. B. Langmuir et al. (Academic Press Inc., New York, 1961), p. 305.