@inbook{NBERc0875,
 Crossref = "NBERbern07-1",
 title = "Technology and the Theory of Vintage Aggregation",
 author = "Michael J. Harper",
 BookTitle = "Hard-to-Measure Goods and Services: Essays in Honor of Zvi Griliches",
 Publisher = "University of Chicago Press",
 pages = "99-120",
 year = "2007",
 month = "October",
 URL = "http://www.nber.org/chapters/c0875",
}
@book{NBERbern07-1,
 title = "Hard-to-Measure Goods and Services: Essays in Honor of Zvi Griliches",
 author = "Ernst R. Berndt and Charles R. Hulten",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2007",
 URL = "http://www.nber.org/books/bern07-1",
}