@inbook{NBERc9831,
 Crossref = "NBERgarb00-1",
 title = "What Does HMO Market Share Measure? Examining Provider Choice Restrictions",
 author = "Laurence Baker",
 BookTitle = "Frontiers in Health Policy Research, Volume 3",
 Publisher = "MIT Press",
 pages = "91-112",
 year = "2000",
 month = "January",
 URL = "http://www.nber.org/chapters/c9831",
}
@book{NBERgarb00-1,
 title = "Frontiers in Health Policy Research, Volume 3",
 author = "Alan M. Garber",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "MIT Press",
 year = "2000",
 URL = "http://www.nber.org/books/garb00-1",
}