@inbook{NBERc3393,
 Crossref = "NBERgron70-1",
 title = "BIBLIOGRAPHY",
 author = "Reuben Gronau",
 BookTitle = "The Value of Time in Passenger Transportation: The Demand for Air Travel",
 Publisher = "UMI",
 pages = "69-71",
 year = "1970",
 URL = "http://www.nber.org/chapters/c3393",
}
@book{NBERgron70-1,
 title = "The Value of Time in Passenger Transportation: The Demand for Air Travel",
 author = "Reuben Gronau",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "UMI",
 year = "1970",
 URL = "http://www.nber.org/books/gron70-1",
}