Kenta Saito Yuki Makita Vu Quang Hitoshi Sasaki Development of a Simulator of Abacus: Ancient Analog Calculator on a Mobile Phone as a Teaching Material. 204-208 2009 HCI (4) http://dx.doi.org/10.1007/978-3-642-02583-9_23 conf/hci/2009-4 db/conf/hci/hci2009-4.html#SaitoMQS09