1. Martin, E.D. "A Design Study of the Inflated Sphere Landing Vehicle, Including the Landing Performance and the Effects of Deviations from Design Conditions," NASA, TechnicalReportNo. TN D-692, April1961.
2. Ross, R.G., Jr. "The Design and Testing of an Inflated Sphere Impact Limiter," Jet Propulsion Laboratory, Technical Report No. 32-1037,December 1966.