1. Schmitendorf, W. E.,Pontryagin's Principle for Problems with Isoperimetric Constraints and for Problems with Inequality Terminal Constraints, Journal of Optimization Theory and Applications, Vol. 18, No. 4, 1976.
2. Hestenes, M. R.,Calculus of Variations and Optimal Control Theory, John Wiley and Sons, New York, New York, 1966.
3. Long, N. V.,Resource Extraction Under the Uncertainty about Possible Nationalization, Journal of Economic Theory, Vol. 10, No. 1, 1975.
4. Long, N. V., andVousden, N.,Optimal Control Theorems, Applications of Control Theory to Economic Analysis, Edited by J. D. Pitchford and S. J. Turnovsky, North Holland Publishing Company, Amsterdam, Holland.
5. Guinn, T.,The Problem of Bounded Space Coordinates as a Problem of Hestenes, SIAM Journal on Control, Vol. 3, pp. 181?190, 1965.