Reid Andersen Christian Borgs Jennifer T. Chayes Uriel Feige Abraham D. Flaxman Adam Kalai Vahab S. Mirrokni Moshe Tennenholtz Trust-based recommendation systems: an axiomatic approach. 199-208 2008 WWW http://doi.acm.org/10.1145/1367497.1367525 conf/www/2008 db/conf/www/www2008.html#AndersenBCFFKMT08