@inproceedings{joel1967commutators,
title={Commutators and systems of singular integral equations. I},
author={Joel David Pincus},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203215856709064},
booktitle={Acta Mathematica},
volume={121},
number={1},
pages={219-249},
year={1967},
}
Joel David Pincus. Commutators and systems of singular integral equations. I. 1967. Vol. 121. In Acta Mathematica. pp.219-249. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203215856709064.