N. Lathia, X. Amatriain, и J. Pujol. (2009)Explores ways of adding "external" rating sources from experts in order to improve collaborative filtering results.
Nearest neighbors does not seem to be always the optimal choice..
B. O’Donovan. (2005)introduces the notion of trust in collaborative filtering.
A simple memory based method is used to incorporate trust into a simple similarity based collaborative filtering algorithm. Results on MovieLens seem to be better than standard methods..
F. Walter, S. Battiston, и F. Schweitzer. (2009)cite arxiv:0902.1475
Comment: Revised, added Empirical Validation, submitted to Recommender Systems
2009.