Wataru Kudo Mao Nishiguchi Fujio Toriumi Fraudulent user detection on rating networks based on expanded balance theory and GCNs. 121-126 2019 ASONAM https://doi.org/10.1145/3341161.3342929 conf/asunam/2019 db/conf/asunam/asonam2019.html#KudoNT19