@inbook {reference/db/Vakali09, title = {Access Control Policy Languages}, booktitle = {Encyclopedia of Database Systems}, year = {2009}, pages = {15-18}, publisher = {Springer US}, organization = {Springer US}, isbn = {978-0-387-39940-9}, author = {Athena Vakali}, editor = {Liu, Ling and Ozsu, M. Tamer} }