Risheng Liu Zhixun Su Zhouchen Lin Xiaoyu Hou Lorentzian Discriminant Projection and Its Applications. 311-320 2009 ACCV (3) http://dx.doi.org/10.1007/978-3-642-12297-2_30 conf/accv/2009-3 db/conf/accv/accv2009-3.html#LiuSLH09