1. Anandakumar, K., Rathipriya, K., & Dr Bharathi, A. (2014). A survey on methodologies for personalized e-Learning recommender systems. International Journal of Innovative Research in Computer and Communication Engineering, 2(6).
2. Anjorin, M., Rensing, C., & Steinmetz, R. (2011).Towards ranking in folksonomies for personalized recommender systems in e-Learning. http://www.crokodil.de , http://demo.crokodil.de .
3. Benhamdi, S., & Seridi, H. (2011).Pedagogical content personalization. In the Proceeding of ITHET’11 Conference (vol. 10), Turkey.
4. Bobadilla, J., Seradella, F., & Hernando, A. (2009). Collaborative filtering adapted to recommender systems of e-Learning. Knowledge-Based Systems, 22, 261–265.
5. Botvinick, M., et al. (2003). Constructive processes in immediate serial recall: A recurrent network model of the bigram frequency effect. In B. Kokinov & W. Hirst (Eds.), Constructive memory (pp. 129–137). Sofia: New Bulgarian University.