1. Atlantic Monthly 1996 The new economics of immigration
2. Ejes y polos de desarrollo en el pasado y el futuro de Venezuela [Development poles in the past and the future of Venezuela];Barrios;Urbana,2002
3. City size distributions and economic development;Berry;Economic Development and Cultural Change,1960
4. Intermediate cities in Latin America: risk and opportunities of coherent urban development;Bolay;Cities,2004