@inproceedings{seppo1983the,
title={The analogue of Picard's theorem for quasiregular mappings in dimension three},
author={Seppo Rickman},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203303982121368},
booktitle={Acta Mathematica},
volume={154},
number={3},
pages={195-242},
year={1983},
}
Seppo Rickman. The analogue of Picard's theorem for quasiregular mappings in dimension three. 1983. Vol. 154. In Acta Mathematica. pp.195-242. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203303982121368.