1. Kharatishvili, G. L.,The Maximum Principle in the Theory of Optimal Processes with Time Lags, Doklady Akad Nauk USSR, Vol. 136, pp. 39–42, 1961.
2. Kharatishvili, G. L.,A Maximum Principle in Extremal Problems with Delays, Mathematical Theory of Control, Edited by A. V. Balakrishnan and L. W. Neustadt, Academic Press, New York, New York, 1967.
3. Eller, D. H., Aggarwal, J. K., andBanks, H. T.,Optimal Control of Linear Time-Delay Systems, IEEE Transactions on Automatic Control, Vol. AC-14, pp. 678–687, 1969.
4. Alekal, Y., Brunovsky, P., Chyung, D. H., andLee, E. B.,The Quadratic Problem for Systems with Time Delays, IEEE Transactions on Automatic Control, Vol. AC-16, pp. 673–687, 1971.
5. Ross, D. W., andFlügge-Lotz, I.,An Optimal Control Problem for Systems with Differential Difference Equation Dynamics, SIAM Journal on Control, Vol. 7, pp. 609–623, 1969.