1. Pontryagin, Boltyanski, Gamkrelidze, Mischenko: “The Mathematical Theory of Optimal Processes», John Wiley & Sons, Inc. N.Y., 1962.
2. W. De Backer:The Generalized Gradient, its Computational Aspects and its Relations to the Maximum Principle, report EUR 411 e. 1963.
3. W. De Backer:The Maximum Principle, its Computational Aspects and its Relations to Other Optimization Techniques., report EUR 590 e. 1964.
4. W. De Backer:Jump Conditions for sensitivity Coefficients report EUR 2198 e. 1964.
5. W. De Backer:Synthesis of Optimal Control and Hybrid Computation report EUR 2202 e. 1964.