1. Pontryagin, L. S., Boltyanskii, V. G., Gamkrelidze, R. V., andMischenko, E. F.,The Mathematical Theory of Optimal Processes, Wiley (Interscience Publishers), New York, New York, 1962.
2. Berkovitz, L. D.,Optimal Control Theory, Springer-Verlag, New York, New York, 1974.
3. Albrecht, F.,Topics in Control Theory, Springer-Verlag, New York, New York, 1968.
4. Hermes, H., andLa Salle, J. P.,Functional Analysis and Time Optimal Control, Academic Press, New York, New York, 1969.
5. Filippov, A. F.,Classical Solutions of Differential Equations with Multivalued Right-Hand Side, SIAM Journal on Control, Vol. 5, pp. 609?621, 1967.