1. “Application of a Low Thrust Trajectory Optimization Scheme to Planar Earth-Mars Transfer,”;Lindorfer;ARS Journal,1962
2. Kelley, H.J., Kopp, R.E., and Moyer, H.G., “A Trajectory Optimization Technique Based upon the Theory of the Second Variation,” presented at the AIAA Astrodynamics Conference, Yale University, Connecticut, August 1963.
3. McGill, R., and Kenneth, P., “A Convergence Theorem on the Iterative Solution of Nonlinear Two-Point Boundary Value Systems,” presented at the XIVth IAF Congress, Paris, France, September 1963.
4. “Method of Gradients,”;Kelley,1962
5. Numerical Methods of Obtaining Solutions of Fixed End Point Problems in the Calculus of Variations;Hestenes,1949