Hiroshi Yoshiura Seiichi Susaki Yasuhiko Nagai Tsukasa Saitoh Hisashi Toyoshima Ryôichi Sasaki Satoru Tezuka INTERNET-MARKs: Clear, Secure, and Portable Visual Marks for the Cyber Worlds. 195-207 1999 conf/spw/1999 Security Protocols Workshop db/conf/spw/spw1999.html#YoshiuraSNSTST99 http://dx.doi.org/10.1007/10720107_26