@inproceedings{stefan1975an,
title={An existence theorem for harmonic mappings of Riemannian manifolds},
author={Stefan Hildebrandt, Helmut Kaul, and Kjell-Ove Widman},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203241717062214},
booktitle={Acta Mathematica},
volume={138},
number={1},
pages={1-16},
year={1975},
}
Stefan Hildebrandt, Helmut Kaul, and Kjell-Ove Widman. An existence theorem for harmonic mappings of Riemannian manifolds. 1975. Vol. 138. In Acta Mathematica. pp.1-16. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203241717062214.