Highly Scalable Deep Learning Training System with Mixed-Precision: Training ImageNet in Four Minutes. - Xianyan Jia; Shutao Song; Wei He; Yangzihao Wang; Haidong Rong; Feihu Zhou; Liqiang Xie; Zhenyu Guo; Yuanzhou Yang; Liwei Yu; Tiegang Chen; Guangxiao Hu; et al. (CoRR, 2018)