Ultra-Low Precision 4-bit Training of Deep Neural Networks - Sun, Xiao; Wang, Naigang; Chen, Chia-Yu; Ni, Jiamin; Agrawal, Ankur; Cui, Xiaodong; Venkataramani, Swagath; El Maghraoui, Kaoutar; Srinivasan, Vijayalakshmi (Viji); Gopalakrishnan, Kailash (Advances in Neural Information Processing Systems, 2020)