@inbook{NBERc6099,
 Crossref = "NBERclot93-1",
 title = "The Growing Concentration of Top Students at Elite Schools",
 author = "Philip J. Cook and Robert H. Frank",
 BookTitle = "Studies of Supply and Demand in Higher Education",
 Publisher = "University of Chicago Press",
 pages = "121-144",
 year = "1993",
 month = "January",
 URL = "http://www.nber.org/chapters/c6099",
}
@book{NBERclot93-1,
 title = "Studies of Supply and Demand in Higher Education",
 author = "Charles T. Clotfelter and Michael Rothschild",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "University of Chicago Press",
 year = "1993",
 URL = "http://www.nber.org/books/clot93-1",
}