@Book {lsf.pki2007,
    editor = {J. Lopez and P. Samarati and J.L. Ferrer},
    booktitle = {Proc. of the 4th European PKI Workshop: Theory and Practice},
    address = {Palma de Mallorca, Spain},
    month = {June},
    day = {28-30},
    year = {2007}
}