1. Babbie, E. (2013). The practice of social research (13th ed.). Belmont: Wadsworth.
2. Beebee, H., Hitchcock, C., & Menzies, P. (Eds.). (2009). The Oxford handbook of causation. Oxford: Oxford University Press.
3. Bentley, J. P. (2005). Principles of measurement systems (4th ed.). New York: Pearson.
4. Borsboom, D. (2006). The attack of the psychometricians. Psychometrika, 71(3), 425–440.
5. Borsboom, D., Mellenbergh, G. J., & Van Heerden, J. (2003). The theoretical status of latent variables. Psychological Review, 110, 203–219.