Baltes, P.B. (1987), Theoretical propositions of life-span developmental psychology: On the dynamics between growth and decline. Developmental Psychology, Vol. 23(5), pp. 611-626.
Gonzales, P., Guzman, J.C., Partelow, L., Pahlke, E., Jocelyn, L., Kastberg, D., and Williams, T. (2004). Highlights from the Trends in International Mathematics and Science Study 2003. United States Department of Education, National Center for Education Statistics. Washington, DC: U.S. Government Printing Office.
Horn, J.L., and Hofer, S.M. (1992), Major abilities and development in the adult period. In R.J. Sternberg and C.A. Berg (Eds.), Intellectual development (pp. 44-49). New York: Cambridge University Press.
Marsiske, M., and Smith, J. (1998), Development of competence: Toward a taxonomy. In T. Husén and T.N. Postlethwaite (Eds.), The International Encyclopedia of Education(Electronic Edition). Oxford: Pergamon Press.
OECD (2003). PISA. Literacy skills for the world of today and tomorrow. Paris: Author.
Postlethwaite, T.N., and Ross, K.N. (1992), Effective schools in reading: An exploratory study. The Hague: The International Association for the Evaluation of Educational Achievement.
Schaie, K.W. (1994), The course of adult intellectual development. American Psychologist, Vol. 49(4), pp. 304-313.
Smith, J., and Marsiske, M. (1997), Abilities and competencies in adulthood: Lifespan perspectives on workplace skills. In A.C. Tuijnman, I.S. Kirsch and D.A. Wagner (Eds.), Adult basic skills: Innovations in measurement and policy analysis (pp 73-114). Cresskill, NJ: Hampton Press, Inc.