Dit-Yan Yeung Hong Chang Guang Dai A Scalable Kernel-Based Algorithm for Semi-Supervised Metric Learning. 1138-1143 2007 conf/ijcai/2007 IJCAI http://dli.iiit.ac.in/ijcai/IJCAI-2007/PDF/IJCAI07-184.pdf db/conf/ijcai/ijcai2007.html#YeungCD07