Yuji Ayatsuka Michimune Kohno Jun Rekimoto Real-World Oriented Access Control Method with a Displayed Password. 19-29 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3101&spage=19 2004 conf/apchi/2004 APCHI db/conf/apchi/apchi2004.html#AyatsukaKR04