@inbook{NBERc7240,
 Crossref = "NBERgril92-1",
 title = "Productivity in the Transportation Sector",
 author = "Robert J. Gordon",
 BookTitle = "Output Measurement in the Service Sectors",
 Publisher = "University of Chicago Press",
 pages = "371-427",
 year = "1992",
 month = "January",
 URL = "http://www.nber.org/chapters/c7240",
}
@book{NBERgril92-1,
 title = "Output Measurement in the Service Sectors",
 author = "Zvi Griliches",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "1992",
 URL = "http://www.nber.org/books/gril92-1",
}