@inproceedings{james1963local,
title={Local behavior of solutions of quasi-linear equations},
author={James Serrin},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203203985857976},
booktitle={Acta Mathematica},
volume={111},
number={1},
pages={247-302},
year={1963},
}