Takashi Nagamatsu Junzo Kamahara Naoki Tanaka Calibration-free gaze tracking using a binocular 3D eye model. 3613-3618 2009 CHI Extended Abstracts http://doi.acm.org/10.1145/1520340.1520543 conf/chi/2009a db/conf/chi/chi2009a.html#NagamatsuKT09