@article{Clark2009,
author = {Clark, G. and Cummins, N. },
title= {Urbanization, Mortality, and Fertility in Malthusian England},
year = {2009},
doi = {10.1257/aer.99.2.242},
journal = {American Economic Review },
volume = {99},
number = {2},
pages = {242--247},
}