@inproceedings{björn2004total, title={Total curvature and rearrangements}, author={Björn E. J. Dahlberg}, url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203614715469869}, booktitle={Arkiv for Matematik}, volume={43}, number={2}, pages={323-345}, year={2004}, }