Kosuke Konishi Naohiro Furukawa Hisashi Ikeda Data model and architecture of a paper-digital document management system. 29-31 2007 ACM Symposium on Document Engineering http://doi.acm.org/10.1145/1284420.1284429 conf/doceng/2007 db/conf/doceng/doceng2007.html#KonishiFI07