Ding Zhou Shenghuo Zhu Kai Yu Xiaodan Song Belle L. Tseng Hongyuan Zha C. Lee Giles Learning multiple graphs for document recommendations. 141-150 2008 WWW http://doi.acm.org/10.1145/1367497.1367517 conf/www/2008 db/conf/www/www2008.html#ZhouZYSTZG08