8United Nations Development Programme. Human development report 2006[M]. New York: Palgrave Macmillan, 2006.
9Social Security Administration (ISA),International Social Security Association (ISSA). Social security programs throughout the world:The Americas,2005[EB/OL]. Washington:SSA Publication No. = 1803.http ://www.ssa.gov/policy/docs/progdesc/ssptw/2004 -2005/americas/ index.html.
10Social Security Administration (SSA),Intemational Social Security Association (ISSA).