@Article {dfjlps-vldb2018,
    author = {S. {De Capitani di Vimercati} and S. Foresti and S. Jajodia and G. Livraga and S. Paraboschi and P. Samarati},
    title = {An Authorization Model for Multi-Provider Queries},
    journal = {Proc. of the VLDB Endowment},
    volume = {11},
    number = {3},
    year = {2018},
    note = {to appear}
}