1. Adserà, A., & Pytliková, M. (2016). Language and migration. In V. A. Ginsburgh & S. Weber (Eds.), The Palgrave handbook of economics and language (pp. 342–372). London: Palgrave Macmillan.
2. Becker, G. S. (1964). Human capital: a theoretical and empirical analysis, with special reference to education. Chicago: University of Chicago Press.
3. Becker, G. S. (1993). Human capital: a theoretical and empirical analysis with special reference to education (3rd ed.). Chicago: University of Chicago Press.
4. Bernaus, M., Masgoret, A.-M., Gardner, R. C., & Reyes, E. (2004). Motivation and attitudes towards learning languages in multicultural classrooms. International Journal of Multilingualism, 1(2), 75–89.
5. Boudon, R. (1974). Education, opportunity, and social inequality: Changing prospects in Western society. New York: Wiley and Sons.