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Unequal futures? : mass higher education and graduates' relative earnings in Portugal, 1995 - 2009
Figueiredo, Hugo, (2013)
Tertiary education in Colombia : paving the way for reform
(2003)
Higher education and earnings : college as an investment and a screening device ; a report prepared for Carnegie Commission on Higher Education and the National Bureau of Economic Research
Taubman, Paul J., (1974)