Engines of the Skill Premium in the Portuguese Economy
Manuel Carlos Nogueira, Óscar Afonso
Ce Sifo Economic Studies, vol. 65, 2019, p. 318-341.

Skill Premium in Portuguese Manufacturing Industries
Manuel Carlos Nogueira, Óscar Afonso, Elias Soukiazis
Applied Economics Letters, vol. 25, 2018, p. 1015-1018.