Valen E. Johnson, Grade Inflation: A Crisis in College Education (New York, 2003).

John Bound, Michael F. Lovenheim, and Sarah Turner, “Increasing Time to Baccalaureate Degree in the United States”, NBER Working Paper 15892, April 2010, p. 13; and Sarah E. Turner, “Going to College and Finishing College. Explaining Different Educational Outcomes”, in Caroline M. Hoxby (ed.) College Choices: The Economics of Whereto Go, When to Go, and How to Pay for It (Chicago, 2004), pp. 13–62, http://www.nber.org/chapters/c10097.