ShengCai Liao Zhen Lei XiangXin Zhu Zhenan Sun Stan Z. Li Tieniu Tan Face Recognition Using Ordinal Features. 40-46 2006 conf/icb/2006 ICB http://dx.doi.org/10.1007/11608288_6 db/conf/icb/icb2006.html#LiaoLZSLT06