1. Goddard, R. H.,A Method of Reaching Extreme Altitudes, Smithsonian Institution, Miscellaneous Collections, Vol. 71, No. 2, 1919.
2. Paiewonsky, B.,Optimal Control: A Review of Theory and Practice, AIAA Journal, Vol. 3, No. 11, 1965.
3. Oldenburger, R.,Optimum Control, Applied Mechanics Reviews, Vol. 17, No. 4, 1964.
4. Leitmann, G.,Rocket Trajectory Optimization, Applied Mechanics Reviews, Vol. 18, No. 5, 1965.
5. Hestenes, M. R.,Numerical Methods of Obtaining Solutions of Fixed End Point Problems in the Calculus of Variations, The RAND Corporation, Memorandum No. RM-102, 1949.