@InProceedings {jssb.sigmod97,
    author = {S. Jajodia and P. Samarati and {V.S.} Subramanian and E. Bertino},
    booktitle = {Proc. of the 1997 ACM International SIGMOD Conference on Management of Data},
    title = {A Unified Framework for Enforcing Multiple Access Control Policies},
    address = {Tucson, AZ},
    month = {May},
    year = {1997}
}