1. Problems of regional economic planning;Boudeville,1966
2. The economic functions of a city in relation to its size;Clark;Econometrica,1945
3. Analysis of central place and point patterns by a nearest neighbour method;Dacey,1962
4. Metropolitanization: the growth of Lagos;Ejiogu,1975
5. Seaports and the economic development of tropical Africa;Hilling,1970