1. A continuous model of transportation;Beckmann;Econometrica,1952
2. Continuous flow modelling in regional science: State of the arts and new perspectives;Beckmann,1980
3. Generic properties of ordinary differential equations;Peixoto,1977
4. Catastrophe theory and its applications;Poston,1978
5. Regional modelling and structural stability;Puu;Environment and Planning A,1979