9FRANKLIN M, WILLIAM F. The unemployment effects of proposed changes in social security,s normal retirement age [ J ]. BusinessEconomics,2006 , 41 (2) : 38 -46.
10Pedro S. Martins, Alvaro A. Novo, Pedro Portugal. Increasing the legal retirement age: the impact on wages, worker flows and firmperformance [ R]. IZA Discussion Paper, No. 4187 , 2009.