@inproceedings{wei1989stability,
title={Stability of Fredholm properties on interpolation scales},
author={Wei Cao, and Yoram Sagher},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203533000013539},
booktitle={Arkiv for Matematik},
volume={28},
number={1},
pages={249-258},
year={1989},
}
Wei Cao, and Yoram Sagher. Stability of Fredholm properties on interpolation scales. 1989. Vol. 28. In Arkiv for Matematik. pp.249-258. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203533000013539.