Honglei Zeng Maher A. Alhossaini Li Ding Richard Fikes Deborah L. McGuinness Computing trust from revision history. 8 2006 PST http://doi.acm.org/10.1145/1501434.1501445 conf/pst/2006 db/conf/pst/pst2006.html#ZengADFM06