Yixiong Liang Weiguo Gong Weihong Li Yingjun Pan Face Recognition Using Heteroscedastic Weighted Kernel Discriminant Analysis. 199-205 2005 conf/icapr/2005-2 ICAPR (2) http://dx.doi.org/10.1007/11552499_23 db/conf/icapr/icapr2005-2.html#LiangGLP05