Ling Liu Jianjun Zhang Wei Han Calton Pu James Caverlee Sungkeun Park Terence Critchlow David Buttler Matthew Coleman 33-60 2006 3 Int. J. Web Service Res. 2 http://www.igi-pub.com/articles/details.asp?ID=5965 db/journals/jwsr/jwsr3.html#LiuZHPCPCBC06