@Article {cms.dke96,
    author = {S. Castano and G. Martella and P. Samarati},
    title = {Analysis, Comparison and Design of Role-Based Security Specifications},
    journal = {Data & Knowledge Engineering (DKE)},
    volume = {21},
    number = {1},
    pages = {31-55},
    month = {December},
    year = {1996}
}