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Regional Economic Development Research Conference, Proceedings, 19.4.1972 : U.S. Department of Commerce, Economic Development Administration
(1972)
Diffusion waves within the context of regional economic development
Hanham, Robert Q., (1976)
Mierniki rozwoju regionów : Główny Urza̧d Statystyczny
(1969)
Modes of propagation of regional economic stagnation, a dynamic perspective
Jutila, Sakari Tapani, (1981)