1. Fiacco, A. V., andMcCormick, G. P.,Nonlinear Programming: Sequential Unconstrained Minimization Techniques, John Wiley and Sons, New York, New York, 1968.
2. Betts, J. T., andCitron, S. J.,Approximate Optimal Control of Distributed Parameter Systems, AIAA Journal, Vol. 10, No. 1, 1972.
3. Betts, J. T.,An Approximation Technique for Determining the Optimal Control of a Distributed Parameter System, Purdue University, Department of Aeronautics, Astronautics, and Engineering Science, Ph.D. Thesis, 1970.
4. Johnson, F. T.,Approximate Finite-Thrust Trajectory Optimization, AIAA Journal, Vol. 7, No. 6, 1969.
5. Taylor, L. W., Jr., Smith, H. J., andIliff, K. W.,Experience Using Balakrishnan's Epsilon Technique to Compute Optimum Flight Profiles, Journal of Aircraft, Vol. 7, No. 2, 1970.