跪求英文文献或相关分析,不胜感激.

Hubbard,B.,and Judd,K.Social Security andIndividual Welfare:Precautionary Saving,Liquidity Constraints and the Payroll Tax[J].American Economic Review,1987

Friedman,Benjamin M.and Warshawsky,Mark,Annuity Yields and Saving in the United States[M].Harvard University.1985,February.