1. Aiken, L. S., & West, S. G. (1991). Multiple regression: Testing and interpreting interactions. Newbury Park: Sage.
2. Alter, A. L., Oppenheimer, D. M., Epley, N., & Eyre, R. N. (2007). Overcoming intuition: metacognitive difficulty activates analytic reasoning. Journal of Experimental Psychology: General, 136, 569–576. doi: 10.1037/0096-3445.136.4.569 .
3. Ayres, P. (2006). Using subjective measures to detect variations of intrinsic cognitive load within problems. Learning and Instruction, 16, 389–400.
4. Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings. In J. Metcalfe & A. Shimamura (Eds.), Metacognition: Knowing about knowing (pp. 185–205). Cambridge: MIT.
5. Bjork, R. A. (2013). Desirable difficulties perspective on learning. In H. Pashler (Ed.), Encyclopedia of the mind (Vol. 4, pp. 134–146). Thousand Oaks: Sage Publication.