Yunsheng Li, Nuno Vasconcelos; Efficient Multi-Domain Learning by Covariance Normalization, Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2019, pp. 5424-5433 https://openaccess.thecvf.com/content_CVPR_2019/html/Li_Efficient_Multi-Domain_Learning_by_Covariance_Normalization_CVPR_2019_paper.html