Takuya Maekawa Yuichi Itoh Norifumi Kawai Yoshifumi Kitamura Fumio Kishino MADO interface: a window like a tangible user interface to look into the virtual world. 175-180 2009 Tangible and Embedded Interaction http://doi.acm.org/10.1145/1517664.1517704 conf/tei/2009 db/conf/tei/tei2009.html#MaekawaIKKK09