1. World Health Statistics 2010 http://www.who.int/whosis/whostat/EN_WHS10_Full.pdf
2. Annual Report on the Aging Society 2009. http://www8.cao.go.jp/kourei/whitepaper/w-2010/zenbun/pdf/1s2s_1_1.pdf
3. Conscious Survey on Older Persons Living Alone 2002 http://www8.cao.go.jp/kourei/ishiki/h14_kiso/pdf/0-1.html
4. Lessons from the Great Hanshin Earthquake http://www.shinsai.or.jp/hrc-e/publish/lessons_ghe/index.html