1. Bouligand, G.,Introduction à la Géométrie Infinitésimale Directe, Gauthier-Villars, Paris, France, 1932.
2. Dubovitskii, A. Ya., andMilyutin, A. A.,Extremum Problems with Constraints, Soviet Mathematics Doklady, Vol. 4, pp. 452?455, 1963.
3. Dubovitskii, A. Ya., andMilyutin, A. A.,Extremum Problems in the Presence of Restrictions, Zurnal Vycislitel'noj Matematiki i Matematiceskoj Fiziki, Vol. 5, pp. 395?453, 1965.
4. Hestenes, M. R.,Calculus of Variations and Optimal Control Theory, John Wiley and Sons, New York, New York, 1966.
5. Halkin, H.,Nonlinear Nonconvex Programming in an Infinite Dimensional Space, Mathematical Theory of Control, Edited by A. V. Balakrishnan and L. W. Neustadt, Academic Press, New York, New York, 1967.