@inproceedings{michael1982$k$-divisibility,
title={$K$-divisibility of the$K$-functional and Calderón couples},
author={Michael Cwikel},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203516825867404},
booktitle={Arkiv for Matematik},
volume={22},
number={1},
pages={39-62},
year={1982},
}
Michael Cwikel. $K$-divisibility of the$K$-functional and Calderón couples. 1982. Vol. 22. In Arkiv for Matematik. pp.39-62. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203516825867404.