@inbook{NBERc8262,
 Crossref = "NBERgrub08-1",
 title = "Do Elderly Workers Substitute for Younger Workers in the United States?",
 author = "Jonathan Gruber and Kevin Milligan",
 BookTitle = "Social Security Programs and Retirement around the World: The Relationship to Youth Employment",
 Publisher = "University of Chicago Press",
 pages = "345-360",
 year = "2010",
 month = "February",
 URL = "http://www.nber.org/chapters/c8262",
}
@book{NBERgrub08-1,
 title = "Social Security Programs and Retirement around the World: The Relationship to Youth Employment",
 author = "Jonathan Gruber and David A. Wise",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2010",
 URL = "http://www.nber.org/books/grub08-1",
}