Iglesias Sánchez, Sara. “Points Based Systems and the Blue Card Directive: Concurrence and Complementarity in the Regulation of Highly Skilled Migration in the European Union”. Migraciones. Publicación Del Instituto Universitario De Estudios Sobre Migraciones, no. 28, Dec. 2013, pp. 157-91, https://revistas.comillas.edu/revistamigraciones/article/view/1261.