Tomomi Yamasaki Toru Nakamura Kensuke Baba Hiroto Yasuura A Door Access Control System with Mobile Phones. 230-240 2007 PWC http://dx.doi.org/10.1007/978-0-387-74159-8_22 conf/ifip6-8/2007 db/conf/ifip6-8/pwc2007.html#YamasakiNBY07