Guang Qiu Bing Liu Jiajun Bu Chun Chen Expanding Domain Sentiment Lexicon through Double Propagation. 1199-1204 2009 IJCAI http://ijcai.org/papers09/Papers/IJCAI09-202.pdf conf/ijcai/2009 db/conf/ijcai/ijcai2009.html#QiuLBC09