See Eric. F. Wolstenholme and D. A. Corben, 1993, "Towards a Core Set of Archetypal Structures in System Dynamics," In: Enrique Zepeda and José A. D. Machuca, eds., The Role of Strategic Modeling in International Competitiveness, Proceedings of the 1993 System Dynamics Conference, Cancún, Mexico, pp. 583-588.