1. Differential Difference Equations;Bellman,1963
2. Optimal control of systems with pure time delays using a variational programming approach;MacKinnon;IEEE Trans. Aut. Control,1967
3. The problem of synthesizing an optimal controller in systems with pure time delay;Chang;Automation Remote Control,1962
4. A time optimal control problem for systems described by difference differential equations,;Oguztoreli;SIAM J. Control,1963
5. Time Lag Control Systems;Oguztoreli,1966