6HAP.T, KEITH. Informal Income Opportunities and Urban Employment in Ghana [J]. Journal of Modern African Studies II , 1975 : 6 ] --89.
7PORTERS A Perspectives on and SCHAUFFLEP~ P~. Competing the Latin American Infopm&l Sector [J]. Population and Development P~eview, 1995 (March): 53 60.
8SETHUIAMAN, S.V. The Urban Informal Sector in Developing Countries: Employment, Poverty and Environment [M]. Geneva, Interna'~ional Labour Office. 1981.
9POff, TES, ALEJANDRO.The Informal Economy and Its Paradoxes [M] // SMESLEP, NElL and PICHAPD SWEBEPG. The Handbook of Economic sociology. Princeton= Princeton University Press, 1994:426-446.
