Weiliang Zhao Vijay Varadharajan George Bryan Modelling Trust Relationships in Distributed Environments. 40-49 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3184&spage=40 2004 conf/trustbus/2004 TrustBus db/conf/trustbus/trustbus2004.html#ZhaoVB04