1. 1) Yamada, M. (2004). Kibo kakusa shakai: makegumi no zetsubou kan ga nihon wo hikisaku (Expected gap-widening society: despair of losers will tear Japan apart). Tokyo: Chikuma shobou.
2. 2) Tachibanaki, T. (1998). Nihon no keizai kakusa: shotoku to shisan kara kangaeru (Economic inequality in Japan: An analysis in terms of income and assets). Tokyo:Iwanami shoten.
3. 3) Otake, F. (2000). 90 nendai no syotoku-kakusa (Income inequality during 1990s). The Monthly Journal of the Japan Institute of Labour, 42, pp.2-11.
4. 4) Sonobe, M. (2001). Gendai daitoshi shakai ron: bunkyokuka suru toshi? (Contemporary Metropolitan Society: Dual City?). Tokyo: Toshindo publishing.
5. 5) Toyoda, T. (1999). The changing spatial structure of a world city, Tokyo: an aspect of social polarization. Journal of Human Sciences and Arts, Faculty of Integrated Arts and Sciences, the University of Tokushima, 6, pp.123-139.