@inproceedings{k.1975regularity, title={Regularity for a class of non-linear elliptic systems}, author={K. Uhlenbeck}, url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203242486958219}, booktitle={Acta Mathematica}, volume={138}, number={1}, pages={219-240}, year={1975}, }