@article{Voland1997,
author = {Voland, E. and Dunbar, R.I.M. and Engel, C. and Stephan, R.},
title= {Population increase and sex-biased parental investment in humans: Evidence from 18th- and 19th-century Germany},
year = {1997},
doi = {10.1086/204593},
journal = {Current Anthropology},
volume = {38},
number = {1},
pages = {129--135},
}