@inproceedings{gunnar1965minimization,
title={Minimization problems for the functional sup_{x}$F(x, f(x), f′(x))$},
author={Gunnar Aronsson},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203433741495039},
booktitle={Arkiv for Matematik},
volume={6},
number={1},
pages={33-53},
year={1965},
}
Gunnar Aronsson. Minimization problems for the functional sup_{x}$F(x, f(x), f′(x))$. 1965. Vol. 6. In Arkiv for Matematik. pp.33-53. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203433741495039.