1. Measure, Integration, and Functional Analysis;Ash,1972
2. Convergence of Probability Measures;Billingsley,1968
3. The maximum principle under minimal hypotheses;Clarke;SIAM J. Control Optim.,1976
4. Necessary conditions for a general control problem;Clarke,1976
5. Generalized gradients and applications;Clarke;Trans. Amer. Math. Soc.,1975