Qualified Targeting Through Data Aggregators in Permissioned Blockchain Settings: A Model for Auditable Transactions. - Miguel-Ángel Sicilia; Pedro Garrido; Salvador Sánchez-Alonso; Marçal Mora Cantallops; Elena García-Barriocanal; Salvador Casquero; Lino González; Alberto Ballesteros-Rodríguez (BLOCKCHAIN, 2020)