The Mechanism of Economic Systems, An Approach to the Problem of Economic Stabilisation from the Point of View of Control-System Engineering R. M. Goodwin; Arnold Tustin The Review of Economics and Statistics 1955 37(2), 209
A Survey of the Mathematical Theory of Time-Lag, Retarded Control and Hereditary Processes Arnold Tustin; Richard Bellman; John M. Danskin Jr. Econometrica 1955 23(3), 354