1. Arrow KJ, Arrow, K.J. Kurz M Kurz, M. (1970) Public investment, the rate of return, and optimal fiscal policy. The John Hopkins Press, Baltimore
2. Bell DJ Bell, D.J. , Jacobson DH Jacobson, D.H. (1975) Singular optimal control. Academic Press, New York
3. Bellman RE Bellman, R.E. (1957) Dynamic programming. Princeton University Press, Princeton
4. Berkovitz LD Berkovitz, L.D. (1961) Variational methods in problems of control and programming. J Math Anal Appl 3:145–169
5. Bettiol P, Bettiol, P. Vinter RB Vinter, R.B. (2010) Sensitivity interpretations of the costate variable for optimal control problems with state constraints. SIAM J Control Optim 48(5):3297–3317