@inbook{NBERc6108,
 Crossref = "NBERcost98-1",
 title = "The Evolution of Retirement",
 author = "Dora L. Costa",
 BookTitle = "The Evolution of Retirement: An American Economic History, 1880-1990",
 Publisher = "University of Chicago Press",
 pages = "6-31",
 year = "1998",
 month = "January",
 URL = "http://www.nber.org/chapters/c6108",
}
@book{NBERcost98-1,
 title = "The Evolution of Retirement: An American Economic History, 1880-1990",
 author = "Dora L. Costa",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "1998",
 URL = "http://www.nber.org/books/cost98-1",
}