@inbook{NBERc12391,
 Crossref = "NBERwise11-1",
 title = "The Long-Run Growth of Disability Insurance in the United States",
 author = "Kevin Milligan",
 BookTitle = "Social Security Programs and Retirement around the World: Historical Trends in Mortality and Health, Employment, and Disability Insurance Participation and Reforms",
 Publisher = "University of Chicago Press",
 pages = "359-389",
 year = "2012",
 month = "September",
 URL = "http://www.nber.org/chapters/c12391",
}
@book{NBERwise11-1,
 title = "Social Security Programs and Retirement around the World: Historical Trends in Mortality and Health, Employment, and Disability Insurance Participation and Reforms",
 author = "David A. Wise",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2012",
 URL = "http://www.nber.org/books/wise11-1",
}