@Article {ds.jcs97,
    author = {S. {De Capitani di Vimercati} and P. Samarati},
    title = {Authorization Specification and Enforcement in Federated Database Systems},
    journal = {Journal of Computer Security (JCS)},
    volume = {5},
    number = {2},
    pages = {155-188},
    year = {1997}
}