Stability analysis of systems with time delay
J. S. Karmarkar, D. D. iljak · Proceedings of the Institution of Electrical Engineers · 1970
An interpretation of Pontryagin's stability criterion for systems with time delay is given in the parameter plane. This leads to a computer-oriented method for analysing stability in terms of 2-variable system parameters. The method is extended to consider nonlinear and multiple-delay systems.