@incollection{liu07rbac,
 author = "Yanhong A. Liu and Scott D. Stoller",
 title = "Role-Based Access Control: {A} Corrected and Simplified Specification",
 editor=" Cliff Wang and Steven King and Ralph Wachter and Robert Herklotz and Chris Arney and Gary Toth and David Hislop and Sharon Heise and Todd Combs",
 booktitle = "Department of Defense Sponsored Information Security Research: New Methods for Protecting Against Cyber Threats",
 publisher = "Wiley",
 year = 2007
}