@inproceedings{avner1968nonlinear,
title={Nonlinear eigenvalue problems},
author={Avner Friedman, and Marvin Shinbrot},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203215301233060},
booktitle={Acta Mathematica},
volume={121},
number={1},
pages={77-125},
year={1968},
}