@techreport{NBERw0743,
 title = "On the Role of Social Security as a Means for Efficient Risk-Bearing in an Economy Where Human Capital Is Not Tradeable",
 author = "Robert C. Merton",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "743",
 year = "1981",
 month = "September",
 URL = "http://www.nber.org/papers/w0743",
}