@InCollection {bs.lead03,
    author = {P. Bonatti and P. Samarati},
    editor = {J. Chomicki and R. {van der Meyden} and G. Saake},
    booktitle = {Logics for Emerging Applications of Databases},
    title = {Logics for Authorizations and Security},
    publisher = {Springer-Verlag},
    year = {2003}
}