1. Asahi Shimbun.27 June 1967. Susumu chūryū kaikyūka: 41-nendo kokumin seikatsu hakusho [Middle class consciousness advancing: White paper on national lifestyle 1966]. Evening edition. 1.
2. Asahi Shimbun.27 January 2006. “Kakusa ga ronten” tsuyomaru: Kakuha kara “ja-kusha Hairyo o” [“The debate on inequality” is heating up: Politicians of all factions show “consideration for the weak”]. 3.
3. Bartolini, Stefano & Peter Mair. 1990.Identity, competition, and electoral availability: The stabilisation of European electorates 1885–1985.Cambridge: Cambridge University Press.
4. BSH Bungei Shunju Henshūbu (ed.). 2006.Ronso: Kakusa shakai[Controversy: Divided society]. Tokyo: Bungei Shunjū.
5. Burniaux, Jean-Marc, Thai-Thang Dang, Douglas Fore, Michael Förster, Marco Mira d’Ércole & Howard Oxley. 1998.Income distribution and poverty in selected OECD countries(OECD Economics Department Working Papers 189). Paris: OECD.