@inproceedings{jens1977solvability,
title={Solvability and alternative theorems for a class of non-linear functional equations in Banach spaces},
author={Jens Frehse},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203505264747308},
booktitle={Arkiv for Matematik},
volume={17},
number={1},
pages={93-105},
year={1977},
}
Jens Frehse. Solvability and alternative theorems for a class of non-linear functional equations in Banach spaces. 1977. Vol. 17. In Arkiv for Matematik. pp.93-105. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203505264747308.