@inbook{NBERc9737,
 Crossref = "NBERfeen03-1",
 title = "The Long Shadow of Patent Expiration. Generic Entry and Rx-to-OTC Switches ",
 author = "Ernst R. Berndt and Margaret Kyle and Davina Ling",
 BookTitle = "Scanner Data and Price Indexes",
 Publisher = "University of Chicago Press",
 pages = "229-274",
 year = "2003",
 month = "January",
 URL = "http://www.nber.org/chapters/c9737",
}
@book{NBERfeen03-1,
 title = "Scanner Data and Price Indexes",
 author = "Robert C. Feenstra and Matthew D. Shapiro",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "2003",
 URL = "http://www.nber.org/books/feen03-1",
}