Saverio Perugini Marcos André Gonçalves Edward A. Fox Recommender Systems Research: A Connection-Centric Survey. 107-143 2004 23 J. Intell. Inf. Syst. 2 http://dx.doi.org/10.1023/B:JIIS.0000039532.05533.99 db/journals/jiis/jiis23.html#PeruginiGF04