1. The time optimal control problem;LaSalle,1960
2. A generalization of LaSalle's bang-bang principle;Halkin;J. SIAM Control,1965
3. The Mathematical Theory of Optimal Processes;Pontryagin,1962
4. On certain questions in the theory of optimal control;Filippov;J. SIAM Control,1962
5. On the “bang-bang” control problem;Bellman;Quart. Appl. Math.,1956