@inproceedings{françois2002vanishing,
title={Vanishing residue characterization of the sine-Gordon hierarchy},
author={François Treves},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203610720655838},
booktitle={Arkiv for Matematik},
volume={42},
number={1},
pages={173-203},
year={2002},
}
François Treves. Vanishing residue characterization of the sine-Gordon hierarchy. 2002. Vol. 42. In Arkiv for Matematik. pp.173-203. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203610720655838.