@inproceedings{björn1972mean,
title={Mean values of subharmonic functions},
author={Björn Dahlberg},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203450285910178},
booktitle={Arkiv for Matematik},
volume={10},
number={1},
pages={293-309},
year={1972},
}