@inbook{NBERc0585,
 Crossref = "NBERgrub07-2",
 title = "Introduction: What Have We Learned about the Problems of and Prospects for Disadvantaged Youth?",
 author = "Jonathan Gruber",
 BookTitle = "The Problems of Disadvantaged Youth: An Economic Perspective",
 Publisher = "University of Chicago Press",
 pages = "1-12",
 year = "2007",
 month = "April",
 URL = "http://www.nber.org/chapters/c0585",
}
@book{NBERgrub07-2,
 title = "The Problems of Disadvantaged Youth: An Economic Perspective",
 author = "Jonathan Gruber",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2009",
 URL = "http://www.nber.org/books/grub07-2",
}