1. Dontchev, A.L.: Perturbations, Approximations and Sensitivity Analysis of Optimal Control Systems. Lecture Notes in Control and Information Sciences, vol. 52. Springer, Berlin (1983)
2. Bellman, R.: Dynamic Programming. Reprint of the sixth 1972 edition. With an introduction by Eric V. Denardo. Dover Publications, Inc., Mineola, NY (2003)
3. Pontryagin, L.S., Boltyanskii, V.G., Gamkrelidze, R.V., Mishchenko, E.F.: The Mathematical Theory of Optimal Processes. Wiley, New York (1962)
4. Boltyanskii, V.G.: The maximum principle in the theory of optimal processes. Dokl. Akad. Nauk SSSR 119, 1070–1073 (1958)
5. Halkin, H.: On the necessary condition for optimal control of non-linear systems. J. Anal. Math. 12, 1–82 (1964)