Ehud Gudes Martin S. Olivier Reind P. van de Riet Modeling, Specifying and Implementing Workflow Security in Cyberspace. 1999 7 Journal of Computer Security 4 db/journals/jcs/jcs7.html#GudesOR99 http://iospress.metapress.com/content/8j3wpab2nr23w9ty/ 287-315