@inproceedings{gunnar1967extension,
title={Extension of functions satisfying lipschitz conditions},
author={Gunnar Aronsson},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203437040998065},
booktitle={Arkiv for Matematik},
volume={6},
number={6},
pages={551-561},
year={1967},
}