Adapting Neural Network to new domain without labels
I think those are one of the most cited papers:


https://arxiv.org/pdf/1409.7495.pdf
http://www.jmlr.org/papers/volume17/15-239/15-239.pdf
http://openaccess.thecvf.com/content_cvpr_2017/paper/Tzeng_Adversarial_Discriminative_Domain_CVPR_2017_paper.pdf
http://openaccess.thecvf.com/content_cvpr_2017/papers/Bousmalis_Unsupervised_Pixel-Level_Domain_CVPR_2017_paper.pdf