Aniello Castiglione Giuseppe Cattaneo Maurizio Cembalo Pompeo Faruolo Umberto Ferraro Petrillo A Multi-scheme and Multi-channel Framework for Micropayment Systems. 62-71 2009 EC-Web http://dx.doi.org/10.1007/978-3-642-03964-5_7 conf/ecweb/2009 db/conf/ecweb/ecweb2009.html#CastiglioneCCFP09