@techreport{NBERr0072,
 title = "A Contribution to the Theory of tax Expenditures: The Case of CharitableGiving",
 author = "Martin Feldstein",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Reprint Series",
 number = "72",
 year = "1980",
 month = "July",
 URL = "http://www.nber.org/papers/r0072",
 abstract = {},
}