Takashi Nagamatsu Junzo Kamahara Takumi Iko Naoki Tanaka One-point calibration gaze tracking based on eyeball kinematics using stereo cameras. 95-98 2008 ETRA http://doi.acm.org/10.1145/1344471.1344496 conf/etra/2008 db/conf/etra/etra2008.html#NagamatsuKIT08