@techreport{NBERw13150,
 title = "The Growth Effect of Democracy: Is It Heterogenous and How Can It Be Estimated?",
 author = "Torsten Persson and Guido Tabellini",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "13150",
 year = "2007",
 month = "June",
 URL = "http://www.nber.org/papers/w13150",
}