@inproceedings{r.1959lebesgue,
title={Lebesgue area of maps from Hausdorff spaces},
author={R. F. Williams},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203152498574888},
booktitle={Acta Mathematica},
volume={102},
number={1},
pages={33-46},
year={1959},
}