@inproceedings{john1957the,
title={The numbers of labeled colored and chromatic trees},
author={John Riordan},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203147130379849},
booktitle={Acta Mathematica},
volume={97},
number={1},
pages={211-225},
year={1957},
}