1. Fixed costs, sunk costs, entry barriers and sustainability of monopoly;Baumol;Quart. J. Econ.,1981
2. External economies of scale and competitive equilibrium;Chipman;Quart. J. Econ.,1970
3. On size, scale and returns: A survey;Gold;J. Econ. Lit.,1981
4. Locational Analysis;Harris,1972
5. Efficiency of Resource Usage and City Size;Henderson;Brown University Working Paper No. 82-14,1982