Context of Models and decision making in national economies : proceedings of the 2nd International Conference on Dynamic Modelling and Control of National Economies : a symposium, organized by Austrian Centre for Efficiency and Productivity (ÖPWZ), 24-27 January 1977, Palais Auersperg, Vienna, Austria ; and sponsored by International Federation of Automatic Control (IFAC), International Institute for Applied Systems Analysis (IIASA), International Federation of Operational Research Societies (IFORS) ; edited by J. M. L. Janssen, L. F. Pau, A. Straszak