@inbook{NBERc0598,
 Crossref = "NBERgrub07-2",
 title = "Neighborhood Violence and Urban Youth",
 author = "Anna Aizer",
 BookTitle = "The Problems of Disadvantaged Youth: An Economic Perspective",
 Publisher = "University of Chicago Press",
 pages = "275-307",
 year = "2007",
 month = "April",
 URL = "http://www.nber.org/chapters/c0598",
}
@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",
}