@techreport{NBERw12018,
 title = "Bias Corrected Estimates of GED Returns",
 author = "James J. Heckman and Paul LaFontaine",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "12018",
 year = "2006",
 month = "February",
 URL = "http://www.nber.org/papers/w12018",
}