@inproceedings{adolph1883note, title={Note sur certaines équations différentielles linéaires}, author={Adolph Steen}, url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108202931725817762}, booktitle={Acta Mathematica}, volume={3}, number={1}, pages={277-282}, year={1883}, }