Valentina Casola Jesus Luna Oscar Manso Nicola Mazzocca Manel Medina Massimiliano Rak Interoperable Grid PKIs Among Untrusted Domains: An Architectural Proposal. 39-51 2007 conf/gpc/2007 GPC http://dx.doi.org/10.1007/978-3-540-72360-8_4 db/conf/gpc/gpc2007.html#CasolaLMMMR07