@inbook{NBERc0055,
 Crossref = "NBERgrub07-1",
 title = "The Budget Impact of Reduced Early Retirement Incentives on the German Public Pension System",
 author = "Axel Börsch-Supan and Simone Kohnz and Reinhold Schnabel",
 BookTitle = "Social Security Programs and Retirement around the World: Fiscal Implications of Reform",
 Publisher = "University of Chicago Press",
 pages = "201-252",
 year = "2007",
 month = "October",
 URL = "http://www.nber.org/chapters/c0055",
}
@book{NBERgrub07-1,
 title = "Social Security Programs and Retirement around the World: Fiscal Implications of Reform",
 author = "Jonathan Gruber and David A. Wise",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2007",
 URL = "http://www.nber.org/books/grub07-1",
}