Mertens, A., and McGinnity, F. (2007). The cost of Flexibility at the Margin. Comparing the Wage Penalty for Fixed-term Contracts in Germany and Spain Using Quantile Regression, Labour, Vol. 21 No. 4-5, December 2007, pp. 637-666, Oxford: Blackwell Publishing, http://dx.doi.org/10.1111/j.1467-9914.2007.00396.x