@inbook{NBERc10857,
 Crossref = "NBERpote01-1",
 title = "Accumulated Pension Collars: A Market Approach to Reducing the Risk of Investment-Based Social Security Reform",
 author = "Martin Feldstein and Elena Ranguelova",
 BookTitle = "Tax Policy and the Economy, Volume 15",
 Publisher = "MIT Press",
 pages = "149-166",
 year = "2001",
 month = "January",
 URL = "http://www.nber.org/chapters/c10857",
}
@book{NBERpote01-1,
 title = "Tax Policy and the Economy, Volume 15",
 author = "James M. Poterba",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "MIT Press",
 year = "2001",
 URL = "http://www.nber.org/books/pote01-1",
}