Zheng Zhao Liang Sun Shipeng Yu Huan Liu Jieping Ye Multiclass Probabilistic Kernel Discriminant Analysis. 1363-1368 2009 IJCAI http://ijcai.org/papers09/Papers/IJCAI09-229.pdf conf/ijcai/2009 db/conf/ijcai/ijcai2009.html#ZhaoSYLY09