@InProceedings {bds.ccs00,
    author = {P. Bonatti and S. {De Capitani di Vimercati} and P. Samarati},
    booktitle = {Proc. of the Seventh ACM Conference on Computer and Communications Security},
    title = {A Modular Approach to Composing Access Control Policies},
    address = {Athens, Greece},
    year = {2000}
}