6Board of Trustees of the Federal Old-Age and Survivors Insurance and Disability Insurance Trust Funds, March 23, 2005,The 2005 Annual Report of the Board of Trustees of the Federal Old-Age and Survivors Insurance and Disability Insurance Trust Funds Communication,Washington, D.C.
7The World Bank, 2005, Old-Age Income support in the 21st Century: An International Perspective on Pension Systems and Reform,The World Bank, Washington DC.
