@Article {ad.istr,
    author = {{C.A.} Ardagna and E. Damiani S. {De Capitani di Vimercati} and P. Samarati},
    title = {XML-based Access Control Languages},
    journal = {Information Security Technical Report},
    volume = {9},
    number = {3},
    pages = {35--46},
    month = {July-September},
    year = {2004}
}