1. T. M. JORDAN, “SIGMA, A Computer Program for Space Radiation Dose Analysis Within Complex Configurations,” DAC-60878, McDonnell Douglas Astronautics Company (1967).
2. W. R. YUCKER and J. R. LILLEY, “CHARGE Code for Space Radiation Shielding Analysis,” DAC-62231, McDonnell Douglas Astronautics Company (1969).