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2. Fattorini, H.O.: The Time Optimal Problem for Distributed Control of Systems Described by the Wave Equation, in: Control Theory of Systems Governed by Partial Differential Equations, edited by A.K. Aziz, J.W. Wingate, M.J. Balas, Academic Press, Inc., 1977, New York, San Francisco, London, pp. 151–175.
3. Hájek, O. and W. Krabs: On a General Method for Solving Time-Optimal Linear Control Problems, in: System Modeling and Optimization, edited by R.G. Drenick and F. Kozin, Springer-Verlag, 1982, Berlin, Heidelberg, New York, pp. 202–208 (also: Preprint No. 579, Fachbereich Mathematik der THD, January 1981).
4. Krabs, W.: Convex Optimization and Approximation, in: Modern Applied Mathematics, edited by B. Korte, North Holland Publishing Company, 1982, Amsterdam, New York, Oxford, pp. 327–357.
5. Krabs, W.: Time-Minimal Controllability in the View of Optimization, in: Optimization and Optimal Control, edited by A. Auslender, W. Oettli, J. Stoer, Springer-Verlag, 1981, Berlin, Heidelberg, New York, pp. 211–217.