1. HEADLEY, L. C., Status of Porous Ionizers for Contact Ionization of Cesium, NASA TN D-3397 (1967)
2. JAMES, E. L., WORLOCK, R. M. et al., Microthruster Development with Simulated Radio-Isotope Heating, AIAA Paper 67–734 (1967). Electric Propulsion and Plasma Dynamics Conference, Colorado Springs, 1967
3. LATHEM, W. C. and STAGGS, J. F., Divergent Flow Contact Ionization Electrostatic Thruster for Satellite Attitude Control and Station Keeping, NASA TN D-4420 (1968)
4. LATHEM, W. C., Ion Accelerator Designs for Kaufman Thrusters, AIAA Paper 69–261, 7th Electric Propulsion Conference, Williamsburg, 1969
5. KAUFMAN, H. R., An Ion Rocket with an Electron-Bombardment Ion Sources, NASA TN D-585 (1961)