@inproceedings{david2003formulae,
title={Formulae for the distance in some quasi-Banach spaces},
author={David E. Edmunds, and Georgi E. Karadzhov},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203613569672860},
booktitle={Arkiv for Matematik},
volume={43},
number={1},
pages={145-165},
year={2003},
}

David E. Edmunds, and Georgi E. Karadzhov. Formulae for the distance in some quasi-Banach spaces. 2003. Vol. 43. In Arkiv for Matematik. pp.145-165. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203613569672860.