@inbook{NBERc11123,
 Crossref = "NBERcutl08-1",
 title = "Inter-Spousal Mortality Effects: Caregiver Burden Across the Spectrum of Disabling Disease",
 author = "Nicholas A. Christakis and Paul D. Allison",
 BookTitle = "Health at Older Ages: The Causes and Consequences of Declining Disability among the Elderly",
 Publisher = "University of Chicago Press",
 pages = "455-477",
 year = "2009",
 month = "January",
 URL = "http://www.nber.org/chapters/c11123",
}
@book{NBERcutl08-1,
 title = "Health at Older Ages: The Causes and Consequences of Declining Disability among the Elderly",
 author = "David M. Cutler and David A. Wise",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2008",
 URL = "http://www.nber.org/books/cutl08-1",
}